Air trap for a medical infusion device

ABSTRACT

An air trap for a blood circuit and method for removing air from blood in a dialysis unit. The air trap may include a blood inlet supply line, a blood outlet supply line, and a container having an approximately spherical internal wall, an inlet at a top end of the container connected to the blood inlet supply line, and an outlet at a bottom end of the container connected to the blood outlet supply line. The inlet may be offset from a vertical axis of the approximately spherical internal wall such that blood entering the container is directed to flow in a spiral-like path. The inlet port may be arranged to introduce blood into the container in a direction that is approximately tangential to the approximately spherical inner wall of the container and/or in a direction that is approximately perpendicular to the vertical axis of the container.

RELATED APPLICATIONS

This application is a division of U.S. application Ser. No. 14/132,838,filed Dec. 18, 2013, now U.S. Pat. No. 9,597,442 issued Mar. 21, 2017,which is a continuation of U.S. application Ser. No. 12/199,166, filedAug. 27, 2008, now abandoned, which is a continuation-in-part of priorU.S. application Ser. No. 12/072,908, filed Feb. 27, 2008, now U.S. Pat.No. 8,246,826 issued Aug. 21, 2012, which claims the benefit of U.S.Provisional Application Ser. No. 60/903,582, filed Feb. 27, 2007 andU.S. Provisional Application Ser. No. 60/904,024, filed Feb. 27, 2007.U.S. application Ser. No. 12/199,166 is also a continuation-in-part ofprior U.S. application Ser. No. 12/038,474, filed Feb. 27, 2008, nowU.S. Pat. No. 8,491,184 issued Jul. 23, 2013, which is acontinuation-in-part of prior U.S. application Ser. No. 11/871,821,filed Oct. 12, 2007 and later abandoned on Mar. 30, 2010, which claimsthe benefit of U.S. Provisional Application Ser. No. 60/921,314, filedApr. 2, 2007 and U.S. Provisional Application Ser. No. 60/904,024, filedFeb. 27, 2007. U.S. application Ser. No. 12/199,166 is also acontinuation-in-part of prior U.S. application Ser. No. 12/038,648,filed Feb. 27, 2008, now U.S. Pat. No. 8,042,563 issued Oct. 25, 2011,which is a continuation-in-part of prior U.S. application Ser. No.11/871,803, filed Oct. 12, 2007, now U.S. Pat. No. 7,967,022 issued Jun.28, 2011, which claims the benefit of U.S. Provisional Application Ser.No. 60/921,314, filed Apr. 2, 2007 and U.S. Provisional Application Ser.No. 60/904,024, filed Feb. 27, 2007. U.S. application Ser. No.12/199,166 is also a continuation-in-part of prior U.S. application Ser.No. 11/871,793, filed Oct. 12, 2007, now U.S. Pat. No. 8,888,470 issuedon Nov. 18, 2014, which claims the benefit of U.S. ProvisionalApplication Ser. No. 60/921,314, filed Apr. 2, 2007 and U.S. ProvisionalApplication Ser. No. 60/904,024, filed Feb. 27, 2007. U.S. applicationSer. No. 12/199,166 is also a continuation-in-part of prior U.S.application Ser. No. 11/871,787, filed Oct. 12, 2007, now abandoned,which claims the benefit of U.S. Provisional Application Ser. No.60/921,314, filed Apr. 2, 2007 and U.S. Provisional Application Ser. No.60/904,024, filed Feb. 27, 2007. U.S. application Ser. No. 12/199,166 isalso a continuation-in-part of prior U.S. application Ser. No.11/871,712, filed Oct. 12, 2007, now U.S. Pat. No. 8,317,492 issued onNov. 27, 2012, which claims the benefit of U.S. Provisional ApplicationSer. No. 60/921,314, filed Apr. 2, 2007 and U.S. Provisional ApplicationSer. No. 60/904,024, filed Feb. 27, 2007. U.S. application Ser. No.12/199,166 is also a continuation-in-part of prior U.S. application Ser.No. 11/871,680, filed Oct. 12, 2007, now U.S. Pat. No. 8,273,049 issuedon Sep. 25, 2012, which claims the benefit of U.S. ProvisionalApplication Ser. No. 60/921,314, filed Apr. 2, 2007 and U.S. ProvisionalApplication Ser. No. 60/904,024, filed Feb. 27, 2007.

FIELD OF INVENTION

The present invention generally relates to hemodialysis and similardialysis systems, e.g., systems able to treat blood or other bodilyfluids extracorporeally.

BACKGROUND

Many factors make hemodialysis inefficient, difficult, and expensive.These factors include the complexity of hemodialysis, the safetyconcerns related to hemodialysis, and the very large amount of dialysateneeded for hemodialysis. Moreover, hemodialysis is typically performedin a dialysis center requiring skilled technicians. Therefore anyincrease in the ease and efficiency of the dialysis process could havean impact on treatment cost or patient outcome.

SUMMARY OF INVENTION

Aspects of the invention generally relate to hemodialysis and similardialysis systems. Illustrative embodiments described herein involve, insome cases, interrelated products, alternative solutions to a particularproblem, and/or a plurality of different uses of one or more systemsand/or articles. Although the various systems and methods describedherein are described in relation to hemodialysis, it should beunderstood that the various systems and method described herein areapplicable to other dialysis systems and/or in any extracorporeal systemable to treat blood or other bodily fluids, such as hemofiltration,hemodiafiltration, etc.

In one aspect of the invention, an enclosure for containing a portablehemodialysis unit is provided, where the hemodialysis unit includessuitable components for performing hemodialysis including a dialyzer,one or more pumps to circulate blood through the dialyzer, a source ofdialysate, and one or more pumps to circulate the dialysate through thedialyzer. The enclosure may include a housing that supports thecomponents of the hemodialysis unit and has a front panel at which bloodcircuit connections and dialysate fluidic connections are located. Forexample, the front panel may support blood line connections for patientblood access, connections for a reagent supply, dialyzer connections forboth blood flow and dialysate, etc. Thus, in one embodiment, an operatormay complete all necessary fluid circuit connections for the bloodcircuit and reagent supply at the housing front panel. The enclosure mayalso include a pair of vertical, side-by-side doors hingedly mounted tothe housing at opposite sides of the front panel so that the doors aremovable between open and closed positions. With the doors in an openposition, an operator may have access to the blood circuit connectionsand dialysate fluidic connections. Also, with the doors in the closedposition, access to the patient access and dialysate fluidic connectionsmay be blocked, and the doors may allow for the retention of heat in thehousing suitable for disinfection during a disinfection cycle. Forexample, at least one of the doors may include a seal to resist airexchange between an interior and an exterior of housing when the doorsare in the closed position to help retain heat and/or help resist entryof dust, dirt or other contaminants.

In one embodiment, each of the vertical, side-by-side doors is mountedto the housing via a hinge plate that is pivotally mounted to the doorat a first end, and is pivotally mounted to the housing at a second endopposite the first end. Thus, the doors may be positionable at two openpositions, e.g., a first open position in which blood circuitconnections and dialysate fluidic connections are exposed and the hingeplate is adjacent the housing, and a second open position in which thehinge plate is positioned away from the housing. One or more retainermembers may be included to maintain the doors in an open positionrelative to a corresponding hinge plate. For example, the retainermember may include at least one magnet attached to the door or the hingeplate that tends to keep the door in an open position relative to thehinge plate and the housing. Also, one or more retainer members maymaintain the hinge plates in a closed position relative to the housing,e.g., in a position close to the housing, and/or maintain the hingeplates in an open position away from the housing.

In one embodiment, at least one of the doors may include a containerholder that is movable between a folded position and an extendedposition in which the container holder is arranged to support acontainer, such as reagent supply container. In addition, oralternately, one or both of the doors may include a hook to support acontrol interface for the hemodialysis unit, such as a remote interfaceunit that is connected to the housing by a communication cable. Thesefeatures may make use of the dialysis unit easier by supportingcomponents in a convenient location.

In another embodiment, the front panel may include at least one flangedportion to support blood lines of a blood circuit assembly. For example,the front panel may include several flanged sections arranged at aperiphery of the front panel, such as at lower corners and at a top edgeof the front panel. Blood circuit lines that connect to a patient may berelatively long (e.g., up to 3-4 feet or more), and may be wrappedaround the periphery of the front panel and retained in place by theflanged portions. The flanged portions may be arranged to support theblood lines and allow the doors to be moved to the closed positionwithout contacting the blood lines, e.g., to avoid pinching of the bloodlines at door hinge points.

In one embodiment, the blood circuit connections at the front panelinclude arterial and venous blood line connectors for the blood circuit,and the dialysate fluidic connections at the front panel include aconnection point for a reagent supply, dialyzer dialysate connections,and a blood line connection point for connecting the arterial and venousblood lines to a directing circuit of the dialysis unit.

The hemodialysis unit may include a control interface that is connectedto the housing by a flexible cable and that is arranged to allow a userto receive information from and provide information to the hemodialysisunit. In one embodiment, the enclosure may include a control interfacemounting area at a top of the enclosure where the control interface ismountable. For example, the control interface may include a foldable legor other support that permits the control interface to be stood in anear vertical orientation on the top of the housing.

In another embodiment, the enclosure may include an electronics sectionthat is separated and insulated from a disinfection section that isheated to disinfect components of the hemodialysis unit. For example,the disinfection section may include all of the liquid circuitcomponents, such as valves, pumps, conduits, etc., of the variousportions of the dialysis unit. The electronics section may includemotors, computers or other data processing devices, computer memory,and/or other temperature sensitive electronics or other components. Byisolating the electronics section from the disinfection section (atleast to some degree), components in the electronics section may bespared exposure to the heat or other environmental conditions in thedisinfection section whether during a disinfection operation orotherwise.

In another aspect of the invention, a portable hemodialysis system maybe arranged so that power for the fluid circuit pumps of a dialysis unitmay be provided by a modular power unit, e.g., a unit that can beselectively connected to or disconnected from the dialysis unit. As aresult, failure of a power unit need not necessarily disable the entiredialysis system. Instead, the power unit may be replaced with anotherpower unit, allowing for treatment to continue. For example, a modularassembly for a portable hemodialysis system may include a dialysis unit,e.g., including a housing that contains suitable components forperforming hemodialysis, such as a dialyzer, one or more pumps tocirculate blood through the dialyzer, a source of dialysate, and one ormore pumps to circulate the dialysate through the dialyzer. The housingmay have a front panel at which blood circuit connections and dialysatefluidic connections are located, e.g., where an operator may makepatient blood access connections, connect a reagent supply, and/orconnect a dialyzer. The modular assembly may also include a power unithaving a housing that contains suitable components for providingoperating power to the pumps of the dialysis unit. The power unit may beselectively connected to the dialysis unit and provide power to thedialysis unit for the pumps when connected to the dialysis unit, but maybe incapable of providing power to the dialysis unit when disconnectedfrom the dialysis unit. The power unit may be selectively connected toand disconnected from the dialysis unit by operation of a single handle,e.g., an operator may turn or otherwise operate a single handle todisconnect the power unit from the dialysis unit. In one embodiment, thedialysis unit and the power unit are sized and weighted to each becarried by hand by a human.

In one embodiment, the pumps of the dialysis unit are pneumatic pumpsand the power unit provides pneumatic power to the dialysis unit. Forexample, the power unit may provide air pressure and/or vacuum to thedialysis unit to power the pumps. The power unit may include one or moreair pressure pumps and/or air vacuum pumps, and the dialysis unit mayinclude a plurality of valves to control application of pneumatic powerto the pumps. To aid with use of the hemodialysis system in the home,the power unit and dialysis unit electrical power requirements may beprovided by standard residential electrical power, e.g., approximately110V, 15 amp electrical power. The dialysis unit may provide electricalpower to the power unit, and the power unit may use the electrical powerto generate operating power for the pumps.

In another aspect of the invention, a blood circuit assembly for adialysis unit may be arranged to allow the replacement of most or allblood circuit components in a single operation. For example, the bloodcircuit assembly may include an organizing tray, a pair of pneumaticpumps mounted to the organizing tray for circulating blood received froma patient through a circuit including a dialyzer unit and returned tothe patient, an air trap mounted to the organizing tray arranged toremove air from blood circulating in the circuit, a pair of dialyzerconnections arranged to connect to the inlet and outlet of a dialyzerunit, and a pair of blood line connectors, one inlet blood lineconnector for receiving blood from the patient and providing blood tothe pneumatic pumps and the other outlet blood line connector forreturning blood to the patient.

In one embodiment, an anticoagulant connection is provided for engagingwith an anticoagulant source and providing anticoagulant into the bloodcircuit. For example, the anticoagulant connection may include a pumpfor pumping anticoagulant from the anticoagulant source, such as heparinfrom a vial of heparin, to the circuit. The anticoagulant connection mayinclude a vial holder arranged to hold two or more differently sizedvials, and a spike to pierce the vial. In one embodiment, the pair ofpneumatic pumps, the anticoagulant connection, and the anticoagulantpump are part of a pump cassette.

In another embodiment, the blood circuit assembly may be selectivelymounted to and removed from a dialysis unit. To aid in handling of theblood circuit assembly, the organizing tray may include a pair ofhandles arranged for gripping by a user. The organizing tray may alsoinclude openings adjacent each of the handles for receiving retainingtabs on a dialysis unit that engage with the blood circuit assembly andretain the blood circuit assembly on the dialysis unit.

In one embodiment, the inlet blood line connector is connected to aninlet for the pump cassette, an outlet for the pump cassette isconnected to a dialyzer inlet connector, a dialyzer outlet connector isconnected to an inlet of the air trap, and an outlet of the air trap isconnected to the outlet blood line connector. The inlet of the air trapmay be located above the outlet of the air trap when the blood circuitassembly is mounted to a dialysis unit, e.g., to aid in trapping of aircirculating in the circuit during treatment. The blood line connectorsmay be arranged for a threaded luer-type connection to a patient access,as well as be arranged for a press-in type connection to the dialysisunit. Such an arrangement may make it easier for an operator to connectthe blood line connectors to the dialysis unit after treatment (e.g.,for later disinfection and/or priming of the blood circuit) whileallowing the connectors to engage with standard luer-type connectors ata patient blood access.

In one embodiment, the organizing tray may include circuit tubeengagement members having a hole or slot through which a respectivecircuit tube passes. The engagement members may engage with therespective circuit tube to allow the circuit tube to be pulled andstretched for engagement with an occluder of the dialysis unit. Forexample, the circuit tubes of the blood circuit assembly may includesilicone tubing that has to be stretched (and thereby reduced indiameter) to engage with an occluder. The circuit tube engagementmembers may resist the pull of an operator on the tubes, allowing thetubes to be stretched and placed in engagement with the occluder.

In another aspect of the invention, a method for replacing a bloodcircuit assembly of a dialysis unit includes grasping a pair of handleson an organizing tray of a blood circuit assembly that is mounted to adialysis unit, disengaging locking tabs of the dialysis unit from theblood circuit assembly to free the blood circuit assembly from thedialysis unit, and pulling on the handles on the organizing tray of theblood circuit assembly to remove the blood circuit assembly from thedialysis unit. Disengagement of the locking tabs may be performed byflexing the locking tabs away from each other such that each locking tabis moved toward a nearest one of the handles. After removal of the bloodcircuit assembly, a replacement blood circuit assembly may be provided,openings in the organizing tray of the replacement blood circuitassembly may be aligned with the locking tabs so that each locking tabis received into a respective opening, and the organizing tray may bepushed relative to the dialysis unit such that the locking tabs engagewith the replacement blood circuit assembly to mount the replacementblood circuit assembly to the dialysis unit. Mounting the replacementblood circuit assembly may also involve connecting control ports on thedialysis unit to mating ports on the assembly so that fluid controlsignals may be provided for pumps and valves of the blood circuitassembly. Other blood circuit connections may be made, such as inlet andoutlet connections for the dialyzer, and the blood line connectors maybe connected to receive dialysate into the blood circuit.

In another aspect of the invention, an air trap for a blood circuit in adialysis unit includes a blood inlet supply line, a blood outlet supplyline, and a container having an approximately spherical internal wall,an inlet at a top end of the container connected to the blood inletsupply line, and an outlet at a bottom end of the container connected tothe blood outlet supply line. The inlet may be offset from a verticalaxis of the approximately spherical internal wall such that bloodentering the container through the inlet is directed to flow in aroundthe approximately spherical wall in a spiral-like path. Such flow in thecontainer may help to remove air bubbles from the blood as it flows fromthe inlet to the outlet, with any removed air remaining near the top ofthe container. The inlet port may be arranged to introduce blood intothe container in a direction that is approximately tangential to theapproximately spherical inner wall of the container and/or in adirection that is approximately perpendicular to the vertical axis ofthe container.

In one embodiment, a self-sealing port may be located at a top of thecontainer, e.g., in the form of a split septum that is arranged topermit introduction of fluid into, and withdrawal of liquid from, thecontainer by inserting a needleless device through the split septum. Theself-sealing port may be arranged to be self-cleaning when disinfectionliquid is circulated through the container, e.g., the port may besuitably exposed to flowing disinfection liquid to remove debris and/orheat material on the port to achieve desired disinfection.

In another aspect of the invention, a tube securing arrangement of ablood circuit assembly includes a organizing tray that supportscomponents of a blood circuit assembly and includes a pair of tubeengagement members each having a hole, a pair of patient inlet andoutlet lines arranged to connect with patient access points forreceiving liquid from and/or providing liquid to the patient, and a pairof stops on the patient inlet and outlet lines, respectively. Thepatient inlet and outlet lines may each pass through a hole of arespective tube engagement member so that the stop engages with the tubeengagement member. With this arrangement, the tube engagement membersmay resist pulling and stretching of the inlet and outlet lines whenengaging the lines with an occluder. The tube engagement members may beflexible to allow a user to press inwardly on the engagement member andseat the respective inlet or outlet line in the occluder, yet resistdownward pulling of the line.

In another aspect of the invention, a hemodialysis system includes adialyzer mount arranged to support a plurality of differently sizedand/or shaped dialyzer units and to accommodate different distancesbetween dialysate connections on the dialyzer units. The dialyzer mount,which may be located on a front panel of the dialysis unit, may includea pair of flange portions that are each arranged to engage with arespective dialysate quick-connect fitting connected to a dialysate portof the dialyzer. Each flange portion may be arranged to engage with agroove on the quick connect fitting that is located between a portion ofthe base of the quick connect fitting and a slide element of the quickconnect fitting. For example, the dialyzer mount may include a pair ofkeyhole features with each keyhole feature having an upper insertionarea sized to receive a portion of the base of the quick-connect fittinginserted into the upper insertion area, and a lower flanged portionhaving a width that is smaller than an overall a width of the base ofthe quick-connect fitting and that engages with a groove on the quickconnect fitting. The lower flanged portion may include a pair ofopposite flanges that engage with the groove and allow the quick-connectfitting to slide along the flanges.

In one embodiment, the bottom keyhole feature may include an adjustablesupport that is moveable in a vertical direction. For example, theadjustable support may be movable along the opposed flanges. Thus, theadjustable support may be fixable in a plurality of different positionson the flanges to support the weight of the dialyzer. In onearrangement, the adjustable support includes a “U” shaped member and atleast one thumb screw that may be tightened to fix the “U” shaped memberin place.

In another aspect of the invention, a blood line connector for a bloodcircuit of a hemodialysis unit may have the ability to make twodifferent types of fluid tight connections, e.g., a screw-typeconnection with a luer connector at a patient access and a press-in typeconnection with a dialysate circuit of the hemodialysis unit. Forexample, the blood line connector may include a tube connection endarranged to sealingly engage with a blood circuit tube, and a patientaccess connection end with a frustoconical member having an internallythreaded portion arranged to engage with an externally threaded patientaccess, and a pair of locking arms extending rearwardly from thefrustoconical member. The locking arms may each have a finger depressionportion and a barbed portion, and may be arranged to engage with amating connector on the dialysis unit at the barbed portions to lock thefrustoconical member in sealing engagement with the mating connectorwhen making a press-in type connection. The barbed portions maydisengage from the mating connector when the finger depression portionsare urged toward each other. In one embodiment, the patient accessconnection end may include a central tube extending from the center ofthe frustoconical member. The internally threaded portion of thefrustoconical member and the central tube may be arranged to mate with afemale luer-type patient access connector or any other suitablescrew-type connection.

In another aspect of the invention, a method for operating a dialysisunit includes connecting blood line connectors of arterial and venousblood lines for a dialysis unit to patient access connectors incommunication with a patient blood system. In one embodiment, thepatient access connectors may require a corresponding blood lineconnector to establish a threaded engagement with the patient accessconnector, thereby forming a luer or screw-type connection between theblood line connectors and the patient access connectors. The dialysisunit may be operated to withdraw blood from a patient access connectorand into an arterial blood line, subject the withdrawn blood to adialysis process to produce treated blood, and return the treated bloodto the patient via the venous blood line and the other patient accessconnector. Thereafter, the blood line connectors may be disconnectedfrom the patient access connectors by unscrewing the blood lineconnectors from a corresponding patient access connector, and the bloodline connectors may be connected to a directing circuit of the dialysisunit. The blood line connectors may be connected to the directingcircuit by a press-in connection with a corresponding connection pointon the dialysis unit, e.g., by pushing the blood line connectors intothe connection points to establish the press-in connection.

In another aspect of the invention, a reagent supply arrangement for ahemodialysis system may be arranged to provide two or more reagentmaterials for use in preparing a dialysate and may include a connectorarranged to help prevent the connection of a reagent material to thewrong port. For example, the reagent supply may include an E-prongconnector having three parallel prongs with two outer prongs arranged ina common plane and a center prong arranged above the common plane, afirst supply line for a first reagent connected in fluid communicationwith one of the outer prongs, a second supply line for a second reagentconnected in fluid communication with the other of the outer prongs, aliquid line connected in fluid communication with the center prong, anda container for housing the first reagent having an inlet connected tothe liquid line and an outlet connected to the first supply line for thefirst reagent. The E-prong connector may help prevent the improperconnection of the first and second supply lines to the dialysis unit,e.g., because the central prong being located out of the plane of thetwo outer prongs ensure connection of the E-prong connector in only oneway to the dialysis unit.

In one embodiment, the container includes a bicarbonate materialsuitable for use in generating a dialysate for the hemodialysis system.The liquid line may be a water supply line that provides water to thecontainer, allowing the water to mix with the bicarbonate (which may bein powder or other solid form) and flow to the first supply line. Thesecond supply line may be an acid supply line that includes a connectorand provides acid material to the E-prong connector. The reagent supplymay also include an acid bag spike that is removably engaged with theconnector of the acid supply line. The acid bag spike may include aspike member and a pair of spring clips at an end of the acid bag spikeopposite the connector of the acid supply line, allowing the acid bagspike to be fluidly connected with an acid bag or other acid source.

In another aspect of the invention, a method for operating ahemodialysis system includes providing a dialysis unit having anenclosure containing suitable components for performing hemodialysisincluding a dialyzer, one or more pumps to circulate blood through thedialyzer, a source of dialysate, and one or more pumps to circulate thedialysate through the dialyzer. The enclosure may include a housing thatsupports the components and has a front panel at which blood circuitconnections and dialysate fluidic connections are made. A reagent supplymay be provided including an E-prong connector, a first supply line fora first reagent connected in fluid communication with one of the outerprongs, a second supply line for a second reagent connected in fluidcommunication with the other of the outer prongs, a liquid lineconnected in fluid communication with the center prong, and a containerfor housing the first reagent having an inlet connected to the liquidline and an outlet connected to the first supply line for the firstreagent. The E-prong connector may be engaged with a connection point atthe front panel of the dialysis unit, thereby allowing the dialysis unitto provide water to the liquid line of the reagent supply, and allowingthe dialysis unit to receive the first and second reagents from thefirst and second supply lines.

Other advantages and novel features of the present invention will becomeapparent from the following detailed description of various non-limitingembodiments of the invention when considered in conjunction with theaccompanying figures. In cases where the present specification and adocument incorporated by reference include conflicting and/orinconsistent disclosure, the present specification shall control. If twoor more documents incorporated by reference include conflicting and/orinconsistent disclosure with respect to each other, then the documenthaving the later effective date shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the invention are described with reference to illustrativeembodiments, which are described with reference to the drawings in whichlike numerals reference like elements, and wherein:

FIG. 1 is a schematic representation of fluid handling components of ahemodialysis system in an illustrative embodiment;

FIG. 2 shows a schematic fluid flow diagram for the dialysis system ofFIG. 1;

FIG. 3 is a schematic fluid flow diagram for the blood flow circuit ofthe FIG. 2 embodiment;

FIG. 4 is a schematic fluid flow diagram for the balancing circuit ofthe FIG. 2 embodiment;

FIG. 5 is a schematic fluid flow diagram for the directing circuit ofthe FIG. 2 embodiment;

FIG. 6 is a schematic fluid flow diagram for the mixing circuit of theFIG. 2 embodiment;

FIG. 7 is a right front perspective view of a hemodialysis system in anillustrative embodiment;

FIG. 8 is a left rear perspective view of the hemodialysis system ofFIG. 7;

FIG. 9 is a front view of the hemodialysis system of FIG. 7;

FIG. 10 is a right front perspective view of the view of thehemodialysis system of FIG. 7 with the doors in a first open position;

FIG. 11 is a top view of the hemodialysis system of FIG. 10;

FIG. 12 is a front view of the hemodialysis system of FIG. 10;

FIG. 13 is a right side view of the hemodialysis system of FIG. 10;

FIG. 14 is a right front perspective view of the view of thehemodialysis system of FIG. 7 with the doors in a second open position;

FIG. 15 is a top view of the hemodialysis system of FIG. 14;

FIG. 16 is a front view of the hemodialysis system of FIG. 14;

FIG. 17 is a front view of the hemodialysis system of FIG. 7 with thedoors in an open position exposing a front panel of the system;

FIG. 18 is a front view of a blood circuit assembly for use with thesystem of FIG. 7;

FIG. 19 right perspective view of a organizing tray for the bloodcircuit assembly of FIG. 18;

FIG. 20 is a left rear perspective view of the blood circuit assembly ofFIG. 18;

FIG. 21 shows a left front perspective view of the front panel of thesystem of FIG. 7;

FIG. 22 shows a front view of the front panel of the system of FIG. 7;

FIG. 23 shows a front view of the front panel of the system of FIG. 7with a pair of mounting features for the dialyzer;

FIG. 24 shows a side view of a dialyzer with quick-connect fittingsattached to the dialysate inlet/outlet ports of the dialyzer;

FIG. 25 shows a right perspective view of a reagent supply for use withthe system of FIG. 7;

FIG. 26 shows a perspective view of an E-prong connector for the reagentsupply of FIG. 25 and a corresponding connection point at the frontpanel of the hemodialysis system;

FIG. 27 shows a perspective view of a pair of blood line connectors forthe blood circuit assembly and a corresponding connection point at thefront panel of the hemodialysis system; and

FIG. 28 shows a side view of a blood line connector and connection pointof FIG. 27.

DETAILED DESCRIPTION

Various aspects of the invention are generally directed to new systemsfor hemodialysis and the like, such as hemofiltration systems,hemodiafiltration systems, plasmapheresis systems, etc. Accordingly,although the various systems and methods described herein are describedin relation to hemodialysis, it should be understood that the varioussystems and method described herein are applicable to other dialysissystems and/or in any extracorporeal system able to treat blood or otherbodily fluids, such as plasma.

As discussed below, a hemodialysis system typically includes a bloodflow path and a dialysate flow path. It should be noted that within suchflow paths, the flow of fluid is not necessarily linear, and there maybe any number of “branches” within the flow path that a fluid can flowfrom an inlet of the flow path to an outlet of the flow path. Examplesof such branching are discussed in detail below. In the blood flow path,blood is drawn from a patient, and is passed through a dialyzer, beforebeing returned to the patient. The blood is treated by the dialyzer, andwaste molecules (e.g., urea, creatinine, etc.) and water are passed fromthe blood, through a semi-permeable membrane in the dialyzer, into adialysate solution that passes through the dialyzer by the dialysateflow path. In various embodiments, blood may be drawn from the patientfrom two lines (e.g., an arterial line and a venous line, i.e., “dualneedle” flow), or in some cases, blood may be drawn from the patient andreturned through the same or catheter needle (e.g., the two lines orlumens may both be present within the same needle, i.e., a form of “duallumen” flow). In still other embodiments, a “Y” site or “T” site isused, where blood is drawn from the patient and returned to the patientthrough one patient connection having two branches (one being the fluidpath for the drawn blood, the second the fluid path for the returnblood, i.e., a form of “single needle” flow). The patient may be anysubject in need of hemodialysis or similar treatments, includingnon-human subjects, such as dogs, cats, monkeys, and the like, as wellas humans.

In the dialysate flow path, fresh dialysate is prepared and is passedthrough the dialyzer to treat the blood from the blood flow path. Thedialysate may also be equalized for blood treatment within the dialyzer(i.e., the pressure between the dialysate and the blood are equalized),often exactly, or in some embodiments, at least within about 1% or about2% of the pressure of the blood. In some cases, it may be desirable tomaintain a greater pressure difference (either positive or negative)between the blood flow path and dialysate flow path. After passingthrough the dialyzer, the used dialysate, containing waste molecules (asdiscussed below), is discarded in some fashion. The dialysate in somecases may be re-circulated in a “multi-pass” arrangement, which may bebeneficial in capturing larger molecules having low mobility across thedialyzer. In some cases, the dialysate is heated prior to treatment ofthe blood within the dialyzer using an appropriate heater, such as anelectrical resistive heater. The dialysate may also be filtered toremove contaminants, infectious organisms, debris, and the like, forinstance, using an ultrafilter. The ultrafilter may have a pore sizechosen to prevent species such as these from passing therethrough. Forinstance, the pore size may be less than about 0.3 micrometers, lessthan about 0.2 micrometers, less than about 0.1 micrometers, or lessthan about 0.05 micrometers, etc. The dialysate is used to draw wastemolecules (e.g., urea, creatinine, ions such as potassium, phosphate,etc.) and water from the blood into the dialysate through osmosis orconvective transport, and dialysate solutions are well-known to those ofordinary skill in the art.

The dialysate typically contains various ions such as sodium, chloride,bicarbonate, potassium and calcium that are similar in concentration tothat of normal blood. In some cases, the bicarbonate, may be at aconcentration somewhat higher than found in normal blood. Typically, thedialysate is prepared by mixing water from a water supply with one ormore ingredients: an “acid” (which may contain various species such asacetic acid, dextrose, NaCl, CaCl, KCl, MgCl, etc.), sodium bicarbonate(NaHCO₃), and/or sodium chloride (NaCl). The preparation of dialysate,including using the appropriate concentrations of salts, osmolarity, pH,and the like, is well-known to those of ordinary skill in the art. Asdiscussed in detail below, the dialysate need not be prepared at thesame rate that the dialysate is used to treat the blood. For instance,the dialysate can be made concurrently or prior to dialysis, and storedwithin a dialysate storage vessel or the like.

Within the dialyzer, the dialysate and the blood typically are separatedby a semi-permeable membrane. Typically, the semipermeable membrane isformed from a polymer such as cellulose, polyarylethersulfone,polyamide, polyvinylpyrrolidone, polycarbonate, polyacrylonitrile, orthe like, which allows the transport of ions or small molecules (e.g.,urea, water, etc.), but does not allow bulk transport or convectionduring treatment of the blood. In some cases (such as high-fluxdialyzers), even larger molecules, such as beta-2-microglobulin, maypass through the membrane. In some cases, for example, ions andmolecules may pass through the dialyzer by convective flow if ahydrostatic pressure difference exists across the semi-permeablemembrane.

It should be noted that, as used herein, “fluid” means anything havingfluidic properties, including but not limited to, gases such as air, andliquids such as water, aqueous solution, blood, dialysate, etc.

FIG. 1 shows a schematic block diagram of fluid circuitry for ahemodialysis system that incorporates various aspects of the invention.In this illustrative embodiment, the dialysis system 5 includes a bloodflow circuit 141 that draws blood from a patient, passes the bloodthrough a dialyzer 14, and returns the treated blood to the patient. Abalancing circuit or an internal dialysate circuit 143 receivesdialysate from an ultrafilter 73, passes the dialysate through thedialyzer 14, and receives used dialysate from the dialyzer 14. Adirecting circuit or an external dialysate circuit 142 provides freshdialysate to the ultrafilter 73, and receives used dialysate from theinternal dialysate circuit 143 (which may be directed to a drain 31).The directing circuit 142 can also receive water from a water supply 30and pass it to a mixing circuit 25. The mixing circuit 25 formsdialysate using water from the directing circuit 142 and reagentingredients 49, such as citric acid, salt and a bicarbonate, that may bereceived from a renewable source. The mixing circuit 25 may preparedialysate, for example, on an as-needed basis, during and/or in advanceof dialysis. New dialysate prepared by the mixing circuit 25 may beprovided to the directing circuit 142, which may provide the dialysateto the ultrafilter 73, as described above. The directing circuit 142 mayinclude a heater to heat the dialysate to a suitable temperature and/orto heat fluid in the system for disinfection. Conduits 67 (shown indotted line) may be connected between the blood flow circuit 141 and thedirecting circuit 142, e.g., for disinfection of the hemodialysissystem.

FIG. 2 is a schematic diagram showing a more detailed circuitarrangement for the dialysis system 5 shown in FIG. 1. It should beunderstood, of course, that FIG. 2 is only one possible embodiment ofthe general hemodialysis system of FIG. 1, and in other embodiments,other fluid circuits, modules, flow paths, layouts, etc. are possible.Examples of such systems are discussed in more detail below, and alsocan be found in the following, each of which is incorporated herein byreference: U.S. application Ser. No. 12/072,908, filed Feb. 27, 2008,U.S. Provisional Application 60/903,582, filed Feb. 27, 2007, U.S.Provisional Application 60/904,024, filed Feb. 27, 2007, U.S. patentapplication Ser. No. 11/871,680, filed Oct. 12, 2007 and published asU.S. Patent Application Publication No. 2008/0208103 on Aug. 28, 2008,U.S. patent application Ser. No. 11/871,712, filed Oct. 12, 2007, U.S.patent application Ser. No. 11/871,787, filed Oct. 12, 2007 andpublished as U.S. Patent Application Publication No. 2008/0253911 onOct. 16, 2008, U.S. patent application Ser. No. 11/871,793, filed Oct.12, 2007 and published as U.S. Patent Application Publication No.2008/0253912 on Oct. 16, 2008, or U.S. patent application Ser. No.11/871,803, filed Oct. 12, 2007 and published as U.S. Patent ApplicationPublication No. 2008/0202591 on Aug. 28, 2008.

The blood flow circuit 141 includes an anticoagulant supply 11 and ablood flow pump 13 which pumps blood from a patient through a dialyzer14 and returns the blood to the patient. The anticoagulant supply 11,although shown in the path of blood flowing towards the dialyzer, may beinstead located in another suitable location. e.g., any locationupstream or downstream from blood flow pump 13. The balancing circuit143 includes two dialysate pumps 15, which pump dialysate into thedialyzer 14, and a bypass pump 35. The flow of blood through the bloodflow circuit 141 in some cases, is synchronized with the flow ofdialysate in the dialysate flow path. In an embodiment, the flow ofdialysate into and out of the dialyzer 14 and the balancing circuit 143is balanced volumewise using balancing chambers in the balancing circuit143. The directing circuit 142 includes a dialysate pump 159, whichpumps dialysate from a dialysate tank 169 through a heater 72 and/or theultrafilter 73 to the balancing circuit 143. The directing circuit 142also receives waste fluid from balancing circuit 143 and directs it to adrain 31. In some cases, the blood flow circuit 141 can be connected viaconduits 67 to the directing circuit 142, e.g., for disinfection, asdiscussed below. Dialysate in the dialysate tank 169 is provided by themixing circuit 25, which produces the dialysate using water from a watersupply 30 provided via the directing circuit 142 and dialysateingredients 49 (e.g., bicarbonate and acid). A series of mixing pumps180, 183, 184 are used to mix the various components and produce thedialysate.

FIG. 3 shows a close-up view of the blood flow circuit 141 in thisillustrative embodiment. Under normal operation, blood flows from apatient through arterial line 203 via blood flow pump 13 to the dialyzer14 (the direction of flow during normal dialysis is indicated by arrows205; in some modes of operation, however, the flow may be in differentdirections, as discussed below). Optionally, an anticoagulant may beintroduced into the blood via anticoagulant pump 80 from ananticoagulant supply. After passing through dialyzer 14 and undergoingdialysis, the blood returns to the patient through venous line 204,optionally passing through an air trap and/or a blood sample port 19.The pump 13 may include, for instance, pumps 23 that are actuated by acontrol fluid.

For example, in one embodiment, the blood flow pump 13 may comprise two(or more) pod pumps 23. Each pod pump, in this particular example, mayinclude a rigid chamber with a flexible diaphragm or membrane dividingeach chamber into a pumping compartment and control compartment. Theremay be four entry/exit valves for these compartments, two for thepumping compartment and two for the control compartment. The valves forthe control compartment of the chambers may be two-way proportionalvalves, one connected to a first control fluid source (e.g., a highpressure air source), and the other connected to a second control fluidsource (e.g., a low pressure air source) or a vacuum source. The fluidvalves can be opened and closed to direct fluid flow when the pod pumps23 are operating. Non-limiting examples of pod pumps are described inU.S. Provisional Application 60/792,073, filed Apr. 14, 2006, or in U.S.patent application Ser. No. 11/787,212, filed Apr. 13, 2007 andpublished as U.S. Patent Application Publication No. 2008/0175719 onJul. 24, 2008, each incorporated herein by reference. If more than onepod pump is present, the pod pumps may be operated in any suitablefashion, e.g., synchronously, asynchronously, in-phase, out-of-phase,etc. For instance, in some embodiments, the two-pump pumps can be cycledout of phase to affect the pumping cycle, e.g., one pump chamber fillswhile the second pump chamber empties. A phase relationship anywherebetween 0° (the pod pumps fill and empty in unison) and 180° (one podpump fills as the other empties) can be selected in order to impart anydesired pumping cycle. A phase relationship of 180° may yield continuousflow into and out of the set of pod pumps. This is useful, for instance,when continuous flow is desired, e.g., for use with dual needle or duallumen catheter flow. Setting a phase relationship of 0°, however, may beuseful in some cases for single needle/single lumen flow or in othercases. In a 0° relationship, the pod pumps will first fill from theneedle, then deliver blood through the blood flow path and back to thepatient using the same needle. In addition, running at phases between 0°and 180° can be used in some cases, to achieve a push/pull relationship(hemodiafiltration or continuous back flush) across the dialyzer.

An anticoagulant (e.g., heparin, or any other suitable anticoagulant)may be contained within a vial 11 (or other anticoagulant supply, suchas a tube or a bag), and blood flow circuit 141 may include a spike 201(which, in one embodiment, is a needle) that can pierce the seal of thevial. The spike 201 may be formed from plastic, stainless steel, oranother suitable material, and may be a sterilizable material in somecases, e.g., the material may be able to withstand sufficiently hightemperatures and/or radiation so as to sterilize the material.

An anticoagulant pump 80, which can act as a metering chamber in somecases, can be used to control the flow of anticoagulant into the bloodcircuit. The anticoagulant pump 80 may be a pod pump or a membrane-basedmetering pump, and/or may be actuated by a control fluid, such as air.For example, the anticoagulant pump 80 may include a rigid chamber witha flexible diaphragm dividing the chamber into a pumping compartment anda control compartment. One valve for the control compartment of thechamber may be connected to a first control fluid source (e.g., a highpressure air source), and the other valve connected to a second controlfluid source (e.g., a low pressure air source) or a vacuum source.Valves for the pumping compartment of the chamber can be opened andclosed in coordination with the control compartment, thus controllingthe flow of anticoagulant into the blood. In one set of embodiments, airprovided through a filter 81 may also be introduced into the blood flowpath by the anticoagulant pump 80, e.g., to provide air into the vial 11after or before anticoagulant is withdrawn from the vial.

Fluid Management System (“FMS”) measurements may be used to measure thevolume of fluid pumped through a pump chamber during a stroke of themembrane, or to detect air in the pumping chamber. FMS methods aredescribed in U.S. Pat. Nos. 4,808,161; 4,826,482; 4,976,162; 5,088,515;and 5,350,357, which are hereby incorporated herein by reference intheir entireties. In one illustrative embodiment, the volume of liquiddelivered by an anticoagulant pump, a dialysate pump, or othermembrane-based fluid pump is determined using an FMS algorithm in whichchanges in chamber pressure are used to calculate a volume measurementat the end of a fill stroke and at the end of a delivery stroke. Thedifference between the computed volumes at the end of fill and deliverystrokes may be used to determine the actual stroke volume. This actualstroke volume can be compared to an expected stroke volume for theparticular sized chamber. If the actual and expected volumes aresignificantly different, the stroke has not properly completed and anerror message can be generated.

The blood flow circuit 141 may also include an air trap 19 to remove airbubbles that may be present within the blood flow path. In some cases,the air trap 19 is able to separate any air that may be present from theblood due to gravity, and/or may include a port for sampling blood.

FIG. 4 shows a close-up view of the balancing circuit 143 in the FIG. 2embodiment. In the balancing circuit 143, dialysate flows from theoptional ultrafilter 73 into a dialysate pump 15. In this embodiment,the dialysate pump 15 includes two pod pumps 161, 162, two balancingchambers 341, 342, and a pump 35 for bypassing the balancing chambers341, 342. The balancing chambers 341, 342 may be constructed such thatthey are formed from a rigid chamber with a flexible diaphragm dividingthe chamber into two separate fluid compartments, so that entry of fluidinto one compartment can be used to force fluid out of the othercompartment and vice versa. Non-limiting examples of pumps that can beused as pod pumps and/or balancing chambers are described in U.S.Provisional Application 60/792,073, filed Apr. 14, 2006, or in U.S.patent application Ser. No. 11/787,212, filed Apr. 13, 2007 andpublished as U.S. Patent Application Publication No. 2008/0175719 onJul. 24, 2008.

In one embodiment, balancing of flow in the internal dialysate circuitworks as follows. A set of pneumatically operated valves 211, 212, 213,241, 242 has its operation synchronized and controlled together, wherevalves 211, 212, 213 are ganged and valves 241 and 242 are ganged, and asecond set of pneumatically operated valves 221, 222, 223, 231, 232similarly have its operation synchronized and controlled together, wherevalves 221, 222, 223 are ganged, and valves 231 and 232 are ganged. At afirst point of time, the first set of valves 211, 212, 213, 241, 242 isopened while the second set of valves 221, 222, 223, 231, 232 is closed.Fresh dialysate flows into balancing chamber 341 while used dialysateflows from dialyzer 14 into pod pump 161. Fresh dialysate does not flowinto balancing chamber 342 since valve 221 is closed. As fresh dialysateflows into balancing chamber 341, used dialysate within balancingchamber 341 is forced out and exits balancing circuit 143 (the useddialysate cannot enter pod pump 161 since valve 223 is closed).Simultaneously, pod pump 162 forces used dialysate present within thepod pump into balancing chamber 342 (through valve 213, which is open;valves 242 and 222 are closed, ensuring that the used dialysate flowsinto balancing chamber 342). This causes fresh dialysate containedwithin balancing chamber 342 to exit the balancing circuit 143 intodialyzer 14. Also, pod pump 161 draws in used dialysate from dialyzer 14into pod pump 161.

Once pod pump 161 and balancing chamber 341 have filled with dialysate,the first set of valves 211, 212, 213, 241, 242 is closed and the secondset of valves 221, 222, 223, 231, 232 is opened. Fresh dialysate flowsinto balancing chamber 342 instead of balancing chamber 341, as valve212 is closed while valve 221 is now open. As fresh dialysate flows intobalancing chamber 342, used dialysate within the chamber is forced outand exits balancing circuit, since valve 213 is now closed. Also, podpump 162 now draws used dialysate from the dialyzer into the pod pump,while used dialysate is prevented from flowing into pod pump 161 asvalve 232 is now closed and valve 222 is now open. Pod pump 161 forcesused dialysate contained within the pod pump (from the previous step)into balancing chamber 341, since valves 232 and 211 are closed andvalve 223 is open. This causes fresh dialysate contained withinbalancing chamber 341 to be directed into the dialyzer 14 (since valve241 is now open while valve 212 is now closed). At the end of this step,pod pump 162 and balancing chamber 342 have filled with dialysate. Thisputs the state of the system back into the configuration at thebeginning of this description, and the cycle is thus able to repeat,ensuring a constant flow of dialysate to and from the dialyzer 14. In anembodiment, the fluid (e.g. pneumatic) pressures on the control side ofthe balancing chamber valves are monitored to ensure they arefunctioning (e.g., opening and closing) properly.

As a specific example, a vacuum (e.g., 4 p.s.i. of vacuum) can beapplied to the port for the first set of valves, causing those valves toopen, while positive pressure (e.g., 20 p.s.i. of air pressure) isapplied to the second set of valves, causing those valves to close (orvice versa). The pod pumps each urge dialysate into one of the volumesin one of the balancing chambers 341, 342. By forcing dialysate into avolume of a balancing chamber, an equal amount of dialysate is squeezedby the diaphragm out of the other volume in the balancing chamber. Ineach balancing chamber, one volume is occupied by fresh dialysateheading towards the dialyzer and the other volume is occupied by useddialysate heading from the dialyzer. Thus, the volumes of dialysateentering and leaving the dialyzer are kept substantially equal.

The bypass pump 35 can direct the flow of dialysate from the dialyzer 14through balancing circuit 143 without passing through either of podpumps 161 or 162. In this embodiment, the bypass pump 35 is a pod pump,similar to those described above, with a rigid chamber and a flexiblediaphragm dividing each chamber into a fluid compartment and a controlcompartment. This pump may be the same or different from the other podpumps and/or metering pumps described above. When control fluid is usedto actuate the bypass pump 35, the additional drop in pressure on theexiting (spent) dialysate side of the dialyzer causes additionalultrafiltration of fluid from the blood in the dialyzer. This may causea net efflux of fluid from the patient's blood, through the dialyzer,and ultimately to drain. Such a bypass may be useful, for example, inreducing the amount of fluid a patient has, which is often increased dueto the patient's inability to excrete excess fluid (primarily water)through the kidneys. As shown in FIG. 4, the bypass pump 35 may becontrolled by a control fluid (e.g., air), irrespective of the operationof pod pumps 161 and 162. This configuration may allow for easiercontrol of net fluid removal from a patient, without having to operatethe inside dialysate pumps either out of balance or out of phase withthe blood pumps in order to achieve such fluid withdrawal from thepatient.

To achieve balanced flow across the dialyzer, the blood flow pump, thepumps of the balancing circuit, and the pumps of the directing circuit(discussed below) may be operated to work together to ensure that flowinto the dialyzer is generally equal to flow out of the dialyzer. Ifultrafiltration is required, the ultrafiltration pump (if one ispresent) may be run independently of some or all of the other bloodand/or dialysate pumps to achieve the desired ultrafiltration rate.

To prevent outgassing of the dialysate, the pumps of the balancingcircuit may be kept at pressures above atmospheric pressure. Incontrast, however, the blood flow pump and the directing circuit pumpsuse pressures below atmosphere to pull the diaphragm towards the chamberwall to complete a fill stroke. Because of the potential of fluidtransfer across the semi-permeable membrane of the dialyzer and becausethe pumps of the balancing circuit run at positive pressures, thebalancing circuit pumps may be able to use information from the bloodflow pump(s) in order to synchronize the delivery strokes of thebalancing circuit chambers to the dialyzer with the delivery strokes ofthe blood pumps.

In one set of embodiments, when running in such a balanced mode, ifthere is no delivery pressure from the blood flow pump, the balancingcircuit pump diaphragm will push fluid across the dialyzer into theblood and the alternate pod of the balancing circuit will not completelyfill. For this reason, the blood flow pump reports when it is activelydelivering a stroke. When the blood flow pump is delivering a stroke theinside dialysate pump operates. When the blood flow pump is notdelivering blood, the valves that control the flow from the dialyzer tothe inside dialysate pumps (and other balancing valves ganged togetherwith these valves, as previously discussed) may be closed to prevent anyfluid transfer from occurring from the dialysate side to the blood side.During the time the blood flow pump is not delivering, the insidedialysate pumps are effectively frozen, and the inside dialysate pumpdelivery stroke resumes once the blood flow pump starts deliveringagain. The inside dialysate pump fill pressure can be set to a minimalpositive value to ensure that the pump operates above atmosphere atminimal impedance. Also, the inside dialysate pump delivery pressure canbe set to the blood flow pump pressure to generally match pressures oneither side of the dialyzer, minimizing flow across the dialyzer duringdelivery strokes of the inside dialysate pump.

In another embodiment, the inside dialysate pump delivers dialysate tothe dialyzer at a pressure slightly above the pressure at which blood isdelivered to the dialyzer. This ensures that a full balance chamber ofclean dialysate gets delivered to the dialyzer. On the return side, theinside dialysate pump can fill with spent dialysate from the dialyzer ata slightly lower pressure than the outlet pressure on the blood side ofthe dialyzer, ensuring that the receiving dialysate pump chamber canfill. This in turn ensures that there is enough dialysate available tocomplete a full stroke in the balancing chamber. Flows across thesemi-permeable membrane caused by these differential pressures will tendto cancel each other; and the pumping algorithm otherwise attempts tomatch the average pressures on the dialysate and blood sides of thedialyzer.

It is generally beneficial to keep the blood flow as continuous aspossible during therapy, as stagnant blood flow can result in bloodclots. In addition, when the delivery flow rate on the blood flow pumpis discontinuous, the balancing pump may pause its stroke morefrequently, which can result in discontinuous and/or low dialysate flowrates. However, the flow through the blood flow pump can bediscontinuous for various reasons. For instance, pressure may be limitedwithin the blood flow pump, e.g., to +600 mmHg and/or −350 mmHg toprovide safe pumping pressures for the patient. For instance, duringdual needle flow, the two pod pumps of the blood flow pump can beprogrammed to run 180° out of phase with one another. If there were nolimits on pressure, this phasing could always be achieved. However toprovide safe blood flow for the patient these pressures are limited. Ifthe impedance is high on the fill stroke (due to a small needle, veryviscous blood, poor patient access, etc.), the negative pressure limitmay be reached and the fill flow rate will be slower then the desiredfill flow rate. Thus the delivery stroke must wait for the previous fillstroke to finish, resulting in a pause in the delivery flow rate of theblood flow pump. Similarly, during single needle flow, the blood flowpump may be run at 0° phase, where the two blood flow pump pod pumps aresimultaneously emptied and filled. When both pod pumps are filled, thevolumes of the two pod pumps are delivered. In an embodiment, thesequence of activation causes a first pod pump and then a second podpump to fill, followed by the first pod pump emptying and then thesecond pod pump emptying. Thus the flow in single needle or single lumenarrangement may be discontinuous.

One method to control the pressure saturation limits would be to limitthe desired flow rate to the slowest of the fill and deliver strokes.Although this would result in slower blood delivery flow rates, the flowrate would still be known and would be more continuous, which wouldallow for more accurate and continuous dialysate flow rates. Anothermethod to make the blood flow rate more continuous in single needleoperation would be to use maximum pressures to fill the pods so the filltime would be minimized. The desired deliver time could then be set tobe the total desired stroke time minus the time that the fill stroketook. However, the less continuous the blood flow, the more thedialysate flow rate may have to be adjusted upward during blood deliveryto the dialyzer to make up for the time that the dialysate pump isstopped when the blood flow pump is filling. If this is done with thecorrect timing, an average dialysate flow rate taken over severalstrokes can still match the desired dialysate flow rate.

FIG. 5 shows a close up of the directing circuit 142 in the FIG. 2embodiment. In this embodiment, the directing circuit 142 can providedialysate from a dialysate tank 169 via a dialysate pump 159 to a heater72 and the ultrafilter 73. The heater 72 may be used to warm thedialysate to body temperature, and/or a temperature such that the bloodin the blood flow circuit is heated by the dialysate, and the bloodreturning to the patient is at body temperature or higher. In somecases, the heater 72 may be connected to a control system such thatdialysate that is incorrectly heated (i.e., the dialysate is too hot ortoo cold) may be recycled (e.g., back to the dialysate tank 169) or sentto drain instead of being passed to the dialyzer. The heater 72 may alsobe used, in some embodiments, for disinfection or sterilizationpurposes. For instance, water may be passed through the hemodialysissystem and heated using the heater such that the water is heated to atemperature able to cause disinfection or sterilization to occur, e.g.,temperatures of at least about 70° C., at least about 80° C., at leastabout 90° C., at least about 100° C., at least about 110° C., etc.

The flow of dialysate through the directing circuit 142 may becontrolled (at least in part) by operation of the dialysate pump 159. Inaddition, the dialysate pump 159 may control flow through the balancingcircuit 143. For instance, as discussed above, fresh dialysate from thedirecting circuit 142 flows into balancing chambers 341 and 342 ofbalancing circuit 143. The dialysate pump 159 may be used as a drivingforce to cause the fresh dialysate to flow into these balancingchambers. In one set of embodiments, dialysate pump 159 includes a podpump, e.g., similar to those described above.

The dialysate may also be filtered to remove contaminants, infectiousorganisms, pathogens, pyrogens, debris, and the like, for instance,using an ultrafilter 73. The ultrafilter 73 may be positioned in anysuitable location in the dialysate flow path, for instance, between thedirecting circuit and the balancing circuit, e.g., as shown, and/or theultrafilter 73 may be incorporated into the directing circuit or thebalancing circuit. If an ultrafilter is used, its pore size may bechosen to prevent species such as these from passing through the filter.

In some cases, the ultrafilter 73 may be operated such that waste fromthe filter (e.g., the retentate stream) is passed to a waste stream,such as waste line 39 in FIG. 5. In some cases, the amount of dialysateflowing into the retentate stream may be controlled. For instance, ifthe retentate is too cold (i.e., heater 72 is not working, or heater 72is not heating the dialysate to a sufficient temperature, the entiredialysate stream (or at least a portion of the dialysate) may bediverted to waste line 39, and optionally, recycled to dialysate tank169 using line 48. Flow from the filter 73 may also be monitored forseveral reasons, e.g., using temperature sensors (e.g., sensors 251 and252), conductivity sensors (for confirming dialysate concentration,e.g., sensor 253), or the like. An example of such sensors is discussedbelow; further non-limiting examples can be seen in a U.S. patentapplication Ser. No. 12/038,474, filed Feb. 27, 2008 and published asU.S. Patent Application Publication No. 2008/0253427 on Oct. 16, 2008.

The ultrafilter and the dialyzer may provide redundant screening methodsfor the removal of contaminants, infectious organisms, pathogens,pyrogens, debris, and the like. Accordingly, any contaminant would haveto pass through both the ultrafilter and the dialyzer before reaching apatient's blood. Even in the event that either the ultrafilter ordialyzer integrity fails, the other may still be able to maintaindialysate sterility and prevent contaminants from reaching the patient'sblood.

The directing circuit 142 may also be able to route used dialysatecoming from a balancing circuit to a drain, e.g., through waste line 39to drain 31. The drain may be, for example, a municipal drain or aseparate container for containing the waste (e.g., used dialysate) to beproperly disposed of. In some cases, one or more check or “one-way”valves (e.g., check valves 215 and 216) may be used to control flow ofwaste from the directing circuit 142 and from the system 5. Also, incertain instances, a blood leak sensor (e.g., sensor 258) may be used todetermine if blood is leaking through the dialyzer 14 into the dialysateflow path. In addition, a liquid sensor can be positioned in acollection pan at the bottom of the hemodialysis unit to indicateleakage of either blood or dialysate, or both, from any of the fluidcircuits.

The directing circuit 142 may receive water from a water supply 30,e.g., from a container of water such as a bag, and/or from a device ableto produce water, e.g., a reverse osmosis device. In some cases, thewater entering the system is set at a certain purity, e.g., having ionconcentrations below certain values. The water entering into thedirecting circuit 142 may be passed on to various locations, e.g., to amixing circuit 25 for producing fresh dialysate and/or to waste line 39.In some cases, valves to the drain 31 and various recycle lines areopened, and conduits 67 may be connected between directing circuit 142and blood flow circuit 141, such that water is able to flow continuouslyaround the system. If heater 72 is also activated, the water passingthrough the system will be continuously heated, e.g., to a temperaturesufficient to disinfect the system.

FIG. 6 shows a close-up view of the mixing circuit 25 in theillustrative embodiment of FIG. 2. Water from the directing circuit 142flows into the mixing circuit 25 due to action of a pump 180. In thisembodiment, the pump 180 includes one or more pod pumps, similar tothose described above. In some cases, a portion of the water is directedto reagent ingredients 49, e.g., for use in transporting theingredients, such as the bicarbonate 28, through the mixing circuit 25.In some cases, sodium chloride and/or the sodium bicarbonate 28 may beprovided in a powdered or granular form, which is mixed with waterprovided by the pump 180. Bicarbonate from bicarbonate source 28 isdelivered via bicarbonate pump 183 to a mixing line 186, which alsoreceives water from the directing circuit 142. Acid from an acid source29 (which may be in a liquid form) is also pumped via an acid pump 184to the mixing line 186. The ingredients 49 (water, bicarbonate, acid,NaCl, etc.) are mixed in mixing chamber 189 to produce dialysate, whichthen flows out of mixing circuit 25 to the directing circuit 142.Conductivity sensors 178 and 179 are positioned along mixing line 186 toensure that as each ingredient is added to the mixing line, it is addedat proper concentrations. The volumes delivered by the water pump 180and/or the other pumps may be directly related to the conductivitymeasurements, so the volumetric measurements may be used as across-check on the composition of the dialysate that is produced. Thismay ensure that the dialysate composition remains safe even if aconductivity measurement becomes inaccurate during a therapy.

FIG. 7 shows a perspective view of a hemodialysis system 5 thatincorporates various aspects of the invention. In accordance with oneaspect of the invention, the system 5 includes a dialysis unit 51 and apower unit module 52 that are shown joined together. In this embodiment,the dialysis unit 51 has a housing that contains suitable components forperforming hemodialysis, such as a dialyzer, one or more pumps tocirculate blood through the dialyzer, a source of dialysate, and one ormore pumps to circulate the dialysate through the dialyzer. For example,the dialysis unit 51 may include the mixing circuit 25, blood flowcircuit 141, the balancing circuit 143 and the directing circuit 142 asdescribed above. The dialysis unit 51 may also include all blood circuitconnections and dialysate fluidic connections needed for operation ofthe system 5. Patient access and other connections may be revealed byopening side-by-side vertical doors 53 via a handle 54 at a front sideof the dialysis unit 51 housing. In this embodiment, the dialysis unit51 includes a control interface 55 (attached to the housing by aflexible cable in this embodiment) that a user may use to controloperation of the dialysis unit 51. The control interface 55 may includea display screen with a touch sensitive overlay to allow touch controland interaction with a graphical user interface presented on the screen.The control interface 55 may also include other features, such as pushbuttons, a speaker, a microphone for receiving voice commands, a digitalcamera, and so on. The back side of the control interface 55 may includea retractable “kick-stand” (not shown) that allows the control interface55 to be positioned on top of the dialysis unit 51 housing. Deployingthe retractable “kick-stand” permits the control interface 55 to beplaced in a near-vertical position to allow proper viewing of thedisplay screen.

The power unit 52 housing may contain suitable components for providingoperating power to the dialysis unit 51, e.g., pneumatic pressure/vacuumto power the pumps, valves and other components of the dialysis unit 51.“Pneumatic,” as used herein, means using air or other gas to move aflexible diaphragm or other member. (It should be noted that air is usedby way of example only, and in other embodiments, other control fluids,such as nitrogen (N₂), CO₂, water, an oil, etc., may be used). Asdiscussed above, the pumps and valves of the dialysis unit 51 mayoperate on pneumatic power, and thus the power unit 52 may provide oneor more pneumatic sources for use by the dialysis unit 51. In this way,the dialysis unit 51 need not necessarily be arranged to generate and/orstore the necessary pneumatic power needed, but instead may rely on thepower unit module 52. The power unit 52 may include one or morepneumatic pumps to generate desired air pressure and/or vacuum, one ormore accumulators or other devices to store pneumatic power, valves,conduits and/or other devices to control flow of pneumatic power in thepower unit 52, as well as a controller having suitable components, suchas a programmed general purpose data processor, memory, sensors (e.g.,to detect pressure, temperature, etc.), relays, actuators, and so on.

In one embodiment, the pneumatic power (e.g., air under suitablepressure/vacuum) may be supplied by the power unit 52 to the dialysisunit 51 via one or more supply tanks or other pressure sources. Forinstance, if two tanks are used in the power unit 52, one supply tankmay be a positive pressure reservoir, and in one embodiment, has a setpoint of 750 mmHg (gauge pressure) (1 mmHg is about 133.3 pascals). Theother supply tank can be a vacuum or negative pressure reservoir, and inone embodiment, has a set point of −450 mmHg (gauge pressure). Thispressure difference may be used, for instance, between the supply tanksand the required pod pump pressure to allow for accurate control of thevariable valves to the pod pumps. The supply pressure limits can be setbased on maximum pressures that can be set for the patient blood flowpump plus some margin to provide enough of a pressure difference forcontrol of the variable valves. Thus, in some cases, the two tanks maybe used to supply pressures and control fluids for all of the dialysisunit 51 functions.

In one embodiment, the power unit 52 may include two independentcompressors to service the supply tanks. Pressure in the tanks can becontrolled using any suitable technique, for instance, with a simple“bang-bang” controller (a controller that exists in two states, i.e., inan on or open state, and an off or closed state), or with moresophisticated control mechanisms, depending on the embodiment. As anexample of a bang-bang controller, for the positive tank, if the actualpressure is less than a set point, the compressor servicing the positivetank is turned on. If the actual pressure is greater than a set point,the compressor servicing the positive tank is turned off. The same logicmay be applied to the vacuum tank and control of the vacuum compressorwith the exception that the sign of the set point term is reversed. Ifthe pressure tanks are not being regulated, the compressor is turned offand the valves are closed.

Tighter control of the pressure tanks can be achieved by reducing thesize of the hysteresis band, however this may result in higher cyclingfrequencies of the compressor. If very tight control of these reservoirsis required, the bang-bang controller could be replaced with aproportional-integral-derivative (“PID”) controller and using pulsewidth modulation (“PWM”) signals on the compressors. Other methods ofcontrol are also possible.

Other pressure sources may be used in other embodiments, and in somecases, more than one positive pressure source and/or more than onenegative pressure source may be used. For instance, more than onepositive pressure source may be used that provides different positivepressures (e.g., 1000 mmHg and 700 mmHg), which may be used to minimizeleakage. For example, high positive pressure can be used to controlvalves, whereas lower positive pressures can be used to control pumps.This limits the amount of pressure that can potentially be sent to thedialyzer or to the patient, and helps to keep actuation of the pumpsfrom overcoming the pressures applied to adjacent valves. A non-limitingexample of a negative pressure is −400 mmHg. In some cases, the negativepressure source may be a vacuum pump, while the positive pressure pumpmay be an air compressor.

Moreover, the power unit 52 may be selectively connectable to thedialysis unit 51, e.g., to allow different power units 52 to beinterchanged. For example, the dialysis unit 51 may be arranged to workwith different types of power units 52, such as power units 52 that useelectrical power to generate the pneumatic power supply, as well aspower units 52 that use stored pneumatic power (e.g., pressurized airstored in one or more high pressure tanks). Thus, a power unit 52 may beinterchanged for another unit 52, in case of failure or otherrequirements. For example, it may be desired to use the system 5 in anarea where noise generation is unacceptable, such as when nearby peopleare sleeping. In this case, it may be desirable to use a power unit 52that uses stored pneumatic power, rather than a unit 52 that generatespneumatic power by running pumps or other noise generating equipment. Asshown in FIG. 8, the power unit 52 may be disconnected from the dialysisunit 51 by manipulating a handle 521. For example, turning the handle521 may unlock the power unit 52 from the dialysis unit 51, disengagingnot only mechanical connections between the housings, but also powerand/or communications connections between the two. An interface (notshown) between the dialysis unit 51 and the power unit 52 may permit theunits to exchange pneumatic power (from the power unit 52 to thedialysis unit 51) as well as electrical power, control communications,and other. The dialysis unit 51 may have connection points forelectrical power (e.g., standard 115V, 15 amp power found in most homepower outlets), external communication (such as Ethernet, or any othersuitable connection suitable for communication), a water supply, and soon. The dialysis unit 51 may provide electrical power or otherconnections to the power unit 52, if desired.

The dialysis unit 51 may include a controller to control flow of controlfluid for various components of the system 5, as well as perform otherdesired functions. In some cases, the control fluid may be held atdifferent pressures within the various tubes or conduits. For instance,some of the control fluid may be held at positive pressure (i.e.,greater than atmospheric pressure), while some of the control fluid maybe held at negative pressures (less than atmospheric pressure). Inaddition, in certain embodiments, the controller may have componentsthat are kept separate from the various liquid circuits. Thisconfiguration has a number of advantages. For example, in oneembodiment, the liquid circuits in the dialysis unit 51 may be heated todisinfection temperatures and/or exposed to relatively high temperaturesor other harsh conditions (e.g., radiation) to effect disinfection,while electronic components of the controller may not be exposed to suchharsh conditions, and may even be kept separate by an insulating wall(e.g., a “firewall”) or the like. That is, the dialysis unit housing mayhave two or more compartments, e.g., one compartment with electronic andother components that may be sensitive to heat or other conditions, andanother compartment with liquid circuit components that are heated orotherwise treated for disinfection.

Thus, in some embodiments, the system 5 may include a “cold” section(which is not heated), and a “hot” section, portions of which may beheated, e.g., for disinfection purposes. The cold section may beinsulated from the hot section through insulation. In one embodiment,the insulation may be molded foam insulation, but in other embodimentscan be any type of insulation, including but not limited to a sprayinsulation, an air space, insulation cut from sheets, etc. In oneembodiment, the cold section includes a circulation system, e.g., a fanand/or a grid to allow air to flow in and out of the cold box. In somecases, the insulation may be extended to cover access points to the“hot” section, e.g., doors, ports, gaskets, and the like. For instance,when the “hot” section is sealed, the insulation may completely surroundthe “hot” section in some cases.

Non-limiting examples of components that may be present within the“cold” section include power supplies, electronics, power cables,pneumatic controls, or the like. In some cases, at least some of thefluids going to and from the “hot” section may pass through the “cold”section; however, in other cases, the fluids may pass to the “hot”section without passing through the “cold” section.

Non-limiting examples of components that may be present within the “hot”section include cassettes (if present), fluid lines, temperature andconductivity sensors, blood leak sensors, heaters, other sensors,switches, emergency lights, or the like. In some cases, some electricalcomponents may also be included in the “hot” section. These include, butare not limited to, a heater. In one embodiment, the heater can be usedto heat the hot box itself, in addition to fluid. In some embodiments,the heater 72 heats the entire “hot” section to reach a desiredtemperature.

In accordance with an aspect of the invention, the dialysis unit 51housing may include vertical side-by-side doors that can be opened toexpose all mechanical interface points for blood flow circuitry andconnections for dialysate circuitry, i.e., all connection points forpatient blood connections and acid/bicarbonate connections, that must bemade by a user to use the dialysis unit 51. FIG. 9 shows a front view ofthe dialysis unit 51 with the vertical side-by-side doors 53 in a closedstate. In this arrangement, the doors 53 may block access to connectionpoints for patient blood connections and acid/bicarbonate connections aswell as seal the interior of the unit housing so as to allow heatretention suitable for disinfection. The seal provided by the doors 53may be hermetic, preventing or substantially resisting any air exchangebetween the housing interior and an exterior environment, or may be of asomewhat lesser quality yet still allow for disinfection.

In this embodiment, the doors 53 are connected to the dialysis unit 51housing by a dual hinge arrangement such that the doors 53 can be openedto two different states of opening. FIGS. 10-13 show the doors 53 in afirst state of opening. In this state, the doors 53 expose all user-madeconnections for the blood circuit connections and for the dialyzercircuitry, including the dialyzer 14 itself and for reagent materials,such as consumable acid/bicarbonate materials. This position alsoexposes several other features, such as holders 531 for anacid/bicarbonate container (not shown) and hooks 532 that may be used tohold any suitable item, such as the control interface 55, which may behung by its handle on one of the hooks 532. (See also FIG. 7 which showsa hook 532 on the front of the left door 53 which may be folded out toreceive the control interface 55 or other item.) The holders 531 in thisembodiment may be folded down from their position shown in the figures(i.e., folded up and into recesses in the doors 53) so as to extendhorizontally from the doors 53. The holders 531 have a “C” shapedreceiving section to receive and hold an acid/bicarbonate container, butof course could be shaped or otherwise arranged in any suitable way.

FIGS. 14-16 show the doors 53 in a second state of opening in which ahinge plate 533 for each door 53 is pivoted outward and away from thedialysis unit housing 51. The hinge plates 533, which in this embodimentextend vertically along almost the entire height of the dialysis unithousing 51, are pivotally attached to the doors 53 at a first, outerend, and are pivotally attached at a second inner end to the dialysisunit housing 51. (Of course, it should be understood that the hingeplates 533 could be arranged and/or positioned differently, e.g., at thetop and bottom of the doors 53 as is found in many refrigerator doorarrangements, each plates 533 may include two or more portions that arevertically separated from each other, etc.) Magnets 534 attached to thehinge plates 533 may interact with corresponding magnets (or othersuitable components, such as a steel elements) attached to the dialysisunit housing 51 so as to attract the hinge plates 533 toward thedialysis unit housing 51, thus tending to keep the hinge plates 533 inthe position shown in FIGS. 10-13. (Of course, the magnets 534 could bepositioned on the unit housing, and the hinge plates 533 could havesuitable elements (such as pieces of steel) that are attracted to themagnets 534.) The doors 53 in this embodiment also include magnetsattached near the hinge plates 533 so that when the doors 53 are openedto the first state as shown in FIGS. 10-13, the magnets interact withcorresponding magnets in the hinge plates 533 to help keep the doors 53in an open position relative to the hinge plate 533. These magnets willalso help maintain the relative position of the doors 53 and the hingeplates 533 when the hinge plates 533 are opened to the second stateshown in FIGS. 13-16.

Although magnets are used in this illustrative embodiment as part of aretainer member to help the doors 53 and/or hinge plates 533 stay in aparticular state of opening or closing, other arrangements for aretainer member are possible. For example, the hinge connection betweenthe doors 53 and the hinge plates 533 and/or the connection between thehinge plates 533 and the housing 51 may include a detent arrangementthat serves to resiliently hold the door 53 or hinge plate 533 in aparticular position relative to the other part (the hinge plate orhousing, respectively). In another embodiment, one or more springs maybe used to help maintain the doors 53 in an open position relative tothe hinge plates 533. In yet another embodiment, the hinge plates 533may have a friction or interference fit with a portion of the housing 51that tends to maintain the hinge plates 533 in the closed position(adjacent the housing). Accordingly, a retainer member that functions tohelp maintain a door 53 in a particular position relative to its hingeplate 533, and/or that functions to help maintain a hinge plate 533 in aparticular position relative to the housing 51, may take any one of anumber of possible arrangements.

In accordance with another aspect of the invention, opening of the doorsto the dialysis unit housing may reveal all of the user-made connectionsfor blood circuit connections and dialysate fluidic connections neededfor operation of the system 5. For example, as shown in FIG. 17, withthe doors 53 in an open position (either the first or second state ofopening) a front panel 511 of the dialysis unit 51 may be exposed. Inthis embodiment, the front panel 511 carries several items or connectionpoints that must be accessed by a user. For example, the dialyzer 14,which must be periodically replaced, is mounted to the front panel 511.The dialyzer 14 must be connected not only to the blood flow circuit141, but also the balancing circuit 143. Also, a connection point 512for an acid/bicarbonate source 49 is located at a lower end of the frontpanel 511. It is at this connection point 512 that a user may connect asource of consumable reagent ingredients 49 used by the dialysis unit 51in making dialysate. An occluder 513 is also mounted on the front panel511. The occluder 513 receives tubes of the blood flow circuit andcontrols the open/closed state of the tubes based on system operation.The function of the occluder 513 is discussed in more detail in U.S.application Ser. No. 12/198,947, filed Aug. 27, 2008 (under AttorneyDocket Number D0570.70020US00 (G28)) and below. In short, the occluder513 allows flow through the arterial and venous lines of the blood flowcircuit unless there is a system problem, such as a leak, pump failure,overpressure situation, etc. In such case, the occluder 513automatically closes the blood lines to prevent all flow to or from thepatient. Also exposed on the front panel 511 are blood line connectionpoints 514 for connecting the arterial and venous blood lines 203, 204of the blood flow circuit 141 with the directing circuit 142 (asexplained above with reference to FIGS. 2 and 3, the blood flow circuit141 may be connected to the directing circuit 142). This connection isnormally made at the end of treatment to allow the system to clean anddisinfect the blood flow circuit 141. The front panel 511 also has a setof control ports 515 that mate with corresponding control ports on theblood pump portion of the blood flow circuit 141. The control ports 515provide controlled levels of air pressure and/or vacuum to control theopen/closed state of valves and to power the pumps of the blood flowcircuit 141.

Also exposed on the front panel 511 is a user control panel 510. Theuser control panel 510 includes one or more buttons permitting the userto bypass the graphical user interface on control interface 55,providing an alternate method to control certain functions (e.g.,critical functions) during hemodialysis. This may be important, forexample, if the control interface 55 should ever fail during a dialysistreatment session. Non-limiting examples of critical functions caninclude a “stop dialysis” or “pause dialysis” command and an “infusedialysate solution” command.

FIG. 17 does not show the arterial and venous lines 203, 204 for theblood flow circuit 141 because in this embodiment and in accordance withanother aspect of the invention, the blood flow circuit 141 is formed asa blood circuit assembly that is removable from the front panel 511 ofthe dialysis unit 51, and the blood circuit assembly is not mounted onthe front panel 511 in FIG. 17. FIG. 18 shows a front view of the bloodcircuit assembly 17 in this embodiment along with the dialyzer 14. Theblood circuit assembly 17 includes various components discussed above,for example with reference to FIG. 3, that are mounted to a bloodcircuit organizing tray 171. The arterial and venous lines 203 and 204(e.g., including lengths of flexible silicone tubing) are terminatedwith blood line connectors that, in one aspect of the invention, arearranged to provide a plug-in or press-in connection with the blood lineconnection points 514 as well as provide a screw-type connection usedwith standard patient access points (e.g., luer type patient accessconnectors). The arterial line 203 leads to an inlet at the top of theblood pump 13, which includes two pod pumps 23, valves and othercomponents for controlling blood flow. Associated with the blood pump 13are an air filter 81, an anticoagulant pump 80 (not shown), and ananticoagulant supply 11 (such as a vial of heparin). (Details regardingthe blood pump 13 in this illustrative embodiment may be found in U.S.patent application Ser. No. 11/871,680, filed Oct. 12, 2007 andpublished as U.S. Patent Application Publication No. 2008/0208103 onAug. 28, 2008, entitled “Pumping Cassette”; U.S. patent application Ser.No. 11/871,712, filed Oct. 12, 2007, entitled “Pumping Cassette”; U.S.patent application Ser. No. 11/871,787, filed Oct. 12, 2007 andpublished as U.S. Patent Application Publication No. 2008/0253911 onOct. 16, 2008, entitled “Pumping Cassette”; U.S. patent application Ser.No. 11/871,793, filed Oct. 12, 2007 and published as U.S. PatentApplication Publication No. 2008/0253912 on Oct. 16, 2008, entitled“Pumping Cassette”; and U.S. patent application Ser. No. 11/871,803,filed Oct. 12, 2007 and published as U.S. Patent Application PublicationNo. 2008/0202591 on Aug. 28, 2008, entitled “Cassette System IntegratedApparatus.”) Blood output from the blood pump 13 (the outlet is locatedat a bottom of the pump 13) flows to an inlet of the dialyzer 14 (at thetop of the dialyzer 14), and out of the dialyzer (the dialyzer bloodoutlet is located at the bottom of the dialyzer 14) to the inlet of theair trap 19. The outlet of the air trap 19 is connected to the venousblood line 204. Connections to the inlet and outlet blood ports of thedialyzer 14 are made with typical screw-type connections.

In accordance with another aspect of the invention, the air trap 19 isplaced in the blood flow path after the blood exits the dialyzer andbefore it is returned to the patient. In an embodiment, air trap 19 canhave a spherical or spheroid-shape container (i.e., a container havingan approximately spherical inner wall), and have its inlet port locatednear the top and offset from the vertical axis of the container, and anoutlet at a bottom of the container. (The vertical axis of the containeris arranged in a vertical direction passing through the top and bottom“poles” of the approximately spherical container.) With the inlet portoffset from the vertical axis (in this case set back toward the tray171), blood is introduced into the container in a direction that isapproximately perpendicular to the vertical axis of the container andthat is approximately tangential to the spherical inner wall of thecontainer. The curved shape of the inside wall of the trap can thusdirect the blood to circulate along the inside wall as the bloodgravitates to the bottom of the container (e.g., in a spiral likefashion), facilitating the removal of air bubbles from the blood. Airpresent in the blood exiting the outlet of the dialyzer 14 will enter atthe top of the air trap 19 and remain at the top of the container asblood flows out the outlet at the bottom and to the venous blood line204. By locating the inlet port near the top of trap 19, it is alsopossible to circulate blood through the trap with minimal or no airpresent within the container (as a “run-full” air trap. The ability toavoid an air-blood interface for routine circulation of blood in thetrap can be advantageous. Placing the inlet port at or near the top ofthe container also allows most or all of the air present in the trap tobe removed from the trap by reversing the flow of fluid through theblood tubing (i.e. from the bottom to the top of the trap 19, exitingthrough the inlet port of the trap 19).

In an embodiment, a self-sealing port, such as a self-sealing stopperwith a split septum or membrane, or another arrangement, is located atthe top of the trap, allowing the withdrawal of air from the container(e.g., by syringe). The blood-side surface of the self-sealing membranecan be situated nearly flush with the top of the interior of the trap,in order to facilitate cleaning of the self-sealing port duringdisinfection, e.g., by reversing flow through the air trap using adialysate or other cleaning fluid. Also, the inlet, outlet and internalwall of the container and the self-sealing port may be arranged tosubstantially eliminate stagnation regions, i.e., allow for few or noregions where blood can stagnate or clot. The self-sealing port can alsoserve as a blood sampling site, and/or to allow the introduction ofliquids, drugs or other compounds into the blood circuit. A sealedrubber-type stopper can be used if access with a needle is contemplated.Using a self-sealing stopper with split septum permits sampling andfluid delivery using a needleless system.

FIG. 19 shows the organizing tray 171 for the blood circuit assembly 17without the various blood circuit assembly 17 components mounted. Inaccordance with one aspect of the invention, the organizing tray 171includes handles 172 (in this embodiment, finger pulls) that a user cangrip when mounting/dismounting the blood circuit assembly 17 to thefront panel 511. Inward of the handles 172 are openings 173 that allowspring tabs on the front panel 511 to pass through and engage with theorganizing tray 171 and/or the blood pump 13 cassette to hold the bloodcircuit assembly 17 in place on the front panel 511. In accordance withanother aspect of the invention, the organizing tray 171 includes bloodline engagement members 174 that each have a C-shaped recess or otherhole through which a corresponding blood line 203, 204 passes. (In thiscontext, a “hole” includes a recess like that shown in FIG. 19, athroughbore that has a continuous wall, e.g., as may be made by a drill,or other suitable opening.) As described in more detail below, the bloodline engagement members 174 are used when mounting the blood lines 203,204 in the occluder 513. In short, when mounting the blood lines 203,204 in the occluder 513, the blood lines 203, 204 must be pulled andstretched downwardly (so as to reduce the outside diameter of the line)while being pushed horizontally into slots for the occluder 513. Theblood line engagement members 174 function to both resist downwardpulling on the blood lines 203, 204 (e.g., each line 203, 204 mayinclude a stop ring above the respective engagement member 174 thatcannot be pulled through the recess in the engagement member 174) aswell as permit the user to press inwardly on the engagement member 174to seat the lines 203, 204 in the occluder slots. The engagement members174 are formed integrally with the organizing tray 171 so that a “livinghinge” or relatively flexible portion of the organizing tray ispositioned between the engagement member 174 and the main body of theorganizing tray 171. This arrangement allows the engagement members 174to be pushed inwardly relative to the organizing tray 171 as theconnection portion between the engagement members 174 and the organizingtray main body flexes.

FIG. 20 shows a rear view of the blood circuit assembly 17 with theorganizing tray 171 removed. This view shows the rear side of the bloodpump 13 section with control ports exposed. These control ports matewith corresponding ports 515 on the front panel 511 (see FIG. 17) sothat pneumatic control (e.g., suitable air pressure or vacuum) can beapplied to the pumps and valves to control their operation and flowthrough the blood circuit assembly 17. FIG. 20 also shows the offset ofthe inlet port of the air trap 19, i.e., the inlet port at the top ofthe air trap 19 is arranged to the rear of the vertical axis of thegenerally spherical container portion of the air trap 19.

FIG. 21 shows a perspective view of the front panel 511 of the dialysisunit 51 with the blood circuit assembly 17 mounted to the front panel511 without the organizing tray 171. (Normally, the blood circuitassembly 17 would include the organizing tray 171, but the tray 171 isnot shown in the example so as to more clearly show components at thefront panel 511.) On opposite sides of the blood pump 13 cassette, thefront panel 511 has spring tabs 516 that extend forwardly andresiliently engage with the blood pump cassette and/or the organizingtray 171 to retain the blood circuit assembly 17 in place. The tabs 516may include a barb or other feature to help retain the blood circuitassembly 17 in place. The spring tabs 516 may be flexed outwardly torelease their hold on the blood circuit assembly 17, allowing itsremoval. However, in the absence of an outwardly directed force on thespring tabs 516, the tabs 516 will remain engaged with the blood circuitassembly 17. FIG. 22 shows a front view of the front panel 511 with theorganizing tray 171 of the blood circuit assembly 17 included. To removethe blood circuit assembly 17 from the front panel 511, a user may placeindex fingers behind the handles 172 while simultaneously placing thumbson the inner side of the spring tabs 516 (the sides nearest the bloodpumps 23) and flexing the spring tabs 516 outwardly and away from thepumps 23. This causes the spring tabs 516 to release the blood circuitassembly 17, e.g., disengagement of barbs on the tabs 516 from the bloodpump 13 and/or the organizing tray 171. Of course, to remove the bloodcircuit assembly 17, other connections must be removed, includingconnections to the dialyzer 14 and the blood line connection points 514,as well as removal of the lines 203, 204 from the occluder 513. Whenmounting the blood circuit assembly 17 to the front panel 511, theorganizing tray 171 may be grasped at the handles 172 and properlyaligned, e.g., so that the spring tabs 516 are aligned to pass throughthe openings 173 and the control ports of the blood pump 13 cassette arealigned with the corresponding ports 515 on the front panel 511. Theblood circuit assembly 17 may then be simply pushed into place, so thatthe spring tabs 516 engage with the organizing tray 171 and/or the bloodpump cassette. Other connections can then be made, such as connectionsto the dialyzer 14, mounting of the blood lines 203,204 with theoccluder 513, etc.

FIG. 21 also shows the slots 517 that hold the blood lines 203, 204 forleading into the occluder 513. The slots 517 define a channel that isslightly smaller than the outside diameter of the blood lines 203, 204so that the lines 203, 204 tend to remain in the slots 517 afterplacement in the slots. This helps to ensure proper association of thelines with the occluder 513. Once the blood circuit assembly 17 ismounted on the spring tabs 516, the user may then engage the blood lines203, 204 with the slots 517 by stretching the lines 203, 204 downward(with the engagement members 174 on the organizing tray 171 engaging thestop ring or other feature on the respective line 203, 204 and resistingthe downward pull) and pushing the lines 203, 204 into a correspondingslot. The lines 203, 204 can be pushed into place by pressing inwardlyon the engagement members 174, which as described above, are flexibleand bend inwardly relative to the organizing tray 171. The lines 203,204 can then be routed through the occluder 513.

In accordance with another aspect of the invention, the front panel 511includes a blood line wrap feature around the periphery of the frontpanel 511. In this illustrative embodiment, the front panel 511 includesflanged portions 518 along the top edge and at lower corners of thefront panel 511. This allows a user to wrap the blood lines 203, 204around the periphery of the front panel 511 by placing the lines 203,204 in a channel defined by the flanged portions 518. The lines 203, 204may be wrapped in a clockwise direction, starting from a point near thebottom of the dialyzer 14, and ending at a point near the lower rightcorner of the front panel 511. The blood lines 203, 204 may then beconnected at the blood line connection points 514, e.g., to allowdisinfecting fluid to be circulated through the blood lines 203, 204. Asa result, the blood lines 203, 204 can be neatly retained on the frontpanel 511, allowing easy access to other components on the front panel511 and allowing the user to close the doors 53 with minimal concern forpinching the blood lines 203, 204 between the doors 53 and the dialyzerunit housing 51. Alternatively, the blood lines 203, 204 may be firstconnected at the blood line connection points 514, and then wrapped in aclockwise direction, starting from a point near the bottom of thedialyzer 14, and ending at a point near the lower right corner of thefront panel 511. This ensures that the blood lines are properlydistributed along the flanged portions 518 to reach the connectionpoints 514. Vertical fences 519 may also be provided along the left andright sides of the front panel 511 to help keep the blood lines 203, 204in a desired position and away from the hinge plates 533 and otherpossible pinch points.

In accordance with another aspect of the invention, the front panel 511of the dialysis unit 51 (or other suitable component) may be arranged toaccommodate a variety of differently sized and/or shaped dialyzer units14. Different patients, and in some cases even the same patient overtime, may be prescribed different dialyzers so as to provide differenttreatment conditions. Thus, the dialysis unit 51 is preferably arrangedto operate with multiple different types of dialyzers 14. In many cases,different dialyzers 14 have different dimensions, such as the overalldiameter and/or length of the dialyzer unit. In this illustrativeembodiment as shown in FIG. 23, the front panel 511 includes a dialyzermount with a pair of “keyhole” features 520 that are arranged to engagewith a respective dialysate quick-connect fitting on the dialyzer 14.Each keyhole feature 520 includes an upper insertion area 520 a sized toreceive a portion of the quick-connect fitting and a lower flangedportion 520 b that has a width that is smaller than an overall diameterof the quick-connect fitting and that engages with a grooved area of thequick-connect fitting. So as to aid in understanding of these features,FIG. 24 shows a dialyzer 14 with quick connect fittings 14 a attached atdialysate inlet and outlet ports of the dialyzer 14. (Blood inlet andoutlet ports are located at the extreme top and bottom of the dialyzer14 shown in FIG. 24.) The quick connect fittings 14 a shown are of astandard type, and most, if not all, dialyzers 14 have dialysateinlet/outlet ports that are arranged to engage with the standard quickconnect fittings 14 a. The quick connect fittings 14 a each include aslide element 14 b that is moved to the right (as shown in FIG. 24)relative to a base 14 c to allow the fitting 14 a to be engaged with adialysate port on the dialyzer 14. When the slide element 14 b is movedto allow the fitting 14 a to be attached to the dialyzer 14, a groove 14d is closed. However, once the fitting 14 a is properly seated on theinlet/outlet port of the dialyzer 14, the slide element 14 b may bereleased, allowing a spring (not shown) to move the slide to the left asshown in FIG. 24, reestablishing the groove 14 d to the condition shownin FIG. 24. Thus, when the quick connect fitting 14 a is properlyengaged with the dialyzer 14, the groove 14 d will be present as shownin FIG. 24.

To mount the dialyzer 14 to the keyhole features 520, the quick connectfittings 14 a may be partially inserted into the upper insertion area520 a of the top and bottom keyhole features, respectively, so that thegroove 14 d of each fitting 14 a is aligned with a flange of the lowerflanged portion 520 b of the keyhole features 520. (Note that the upperinsertion area 520 of the bottom keyhole feature 520 may be made longerthan that shown in FIG. 23 to allow the accommodation of a wider rangeof dialyzer lengths.) With the grooves 14 d aligned with the flanges,the dialyzer 14 may be lowered so that the quick connect fittings 14 aare fully received into the lower flanged portions 520 b of the keyholefeatures 520.

In accordance with another aspect of the invention, one or both of thekeyhole features 520 may be adjustable so that the weight of thedialyzer 14 is shared by both lower flanged portions 520 b of thekeyhole features 520. For example, in this illustrative embodiment, thebottom keyhole feature 520 has part of the lower flanged portion 520 badjustable in vertical position relative to the top keyhole feature 520.In this way, the portion of the lower flanged portion 520 b may beadjusted in vertical position so that, with the top quick connectfitting 14 a supported by the flanged portion 520 b of the top keyholefeature 520, the movable portion of the flanged portion 520 b of thebottom keyhole feature can be moved, e.g., upwardly, so that the bottomquick connect fitting 14 a is also supported by the flanged portion 520b. Thus, the weight of the dialyzer 14 can be shared by both keyholefeatures 520. The flanged portion 520 b may be made adjustable in anysuitable way. In this embodiment, the flanged portion 520 b has a “U”shaped member 520 c that is vertically slidable along the verticalflanges and can be fixed in place by tightening a set of thumb screws.The “U” shaped member 520 c may engage the quick connect fitting 14 a sothat the “U” shaped member 520 c supports the weight (at least in part)of the dialyzer 14.

Although in the embodiment above, the dialyzer 14 is supported bykeyhole features in the front panel 511, a support arrangement for thedialyzer may be configured in other ways. For example, the upperinsertion area 520 a is not necessarily required. Instead, only flangeportions (e.g., in the shape of a “U” shaped flange having opposedflange portions) may be provided to engage the dialyzer quick connectfittings. The flange portions may be offset from the front surface ofthe front panel 511 to provide clearance for the fitting and allow theflange portions to engage with the grooves of the quick connectfittings. Also, the flange portions need not be provided in a verticalorientation as shown, but instead may be oriented at an angle to thevertical, e.g., in a horizontal arrangement. The flange portions mayhave a detent, catch, or other feature to help maintain the dialyzer inplace as well.

In accordance with another aspect of the invention, a bicarbonate, acidand/or other reagent supply device may be selectively associated withthe dialysis unit. As described above, the dialysis unit 51 requires asupply of certain chemicals to generate dialysate and/or other materialsneeded for system operation. FIG. 25 shows a reagent supply 49 used toprovide acid, bicarbonate and/or other materials to the dialysis unit52. (FIG. 21 shows the reagent supply 49 attached to theacid/bicarbonate connection point 512 on the front panel 511.) Thereagent supply 49 in this illustrative embodiment includes an E-prongconnector 491 that is arranged to mate with the acid/bicarbonateconnection point 512. As with other connections made by the user at thefront panel 511, e.g., including the blood line connections at theconnection point 514, the mating connectors may be color coded orotherwise marked to help ensure proper connections are made. Forexample, the E-prong connector 491 and the acid/bicarbonate connectionpoint 512 may be colored orange, while the arterial line 203 and itsmating connection at the connection point 514 may be colored red, andthe venous line 204 and its mating connection at the connection point514 are colored blue. Leading from the E-prong connector 491 are abicarbonate supply line 492, a water supply line 493 and an acid supplyline 494. (See FIG. 6 and the accompanying description regarding thefunction of these lines.) The water supply line 493 provides water to abicarbonate supply 28 (which in this embodiment is a 750 g AltracartBicarbonate cartridge (#500750A) sold by Baxter International Inc. thatincludes a powdered bicarbonate material, but may be any suitablesupply), which provides bicarbonate to the dialysis unit 51 via thebicarbonate supply line 492. In this embodiment, the acid supply line494 leads to an acid bag spike 495, which may be used to pierce and drawa suitable acid from a IV-type bag or other container. In thisembodiment, the acid bag spike 495 includes a spike member 495 a and apair of spring clips 495 b. The spring clips 495 b are joined togetherat center portions by a connecting bar such that the spring clips 495 band the connecting bar form an “H” shape and allow the spring clips 495b to be pivoted relative to each other when proximal ends of the springclips 495 b are squeezed toward each other. The spring clips 495 b maybe arranged to engage with a connector element on an acid bag (or otheracid supply, not shown) so that the spike member 495 a remains engagedwith the bag until a user disengages the clips 495 b. For example,distal ends of the clips 495 b may include barbs that engage with theacid supply, and the clips may be disengaged from the acid supply bysqueezing proximal ends of the clips 495 b together to disengage thebarb elements at the distal ends of the clips 495 b from the acidsupply. The acid bag spike 495 may also include a valve 495 c (in thiscase, a pinch clamp) to open/close the line of the acid bag spike 495.In accordance with one aspect of the invention, the acid bag spike 495may be replaced (disconnected from the acid supply line 494 at a capconnector 496) with another component, such as an acid jug straw (notshown) or other arrangement. When used with a jug straw, the capconnector 496 may be engaged with an acid jug opening such that the capconnector 496 covers the opening, like a cap. Alternatively, the jugstraw can terminate in a spike, which then has the ability to penetratea self-sealing (e.g. rubber) membrane covering the opening of the acidjug. Thus, different types of components may be attached to the acidsupply line 494 depending on the acid supply arrangement (such as a jug,bottle, bag, or other).

FIG. 26 shows a close up view of the E-prong connector 491 and thecorresponding connection point 512 at the front panel 511. The E-prongconnector 491 has three parallel prongs (corresponding to thebicarbonate and acid supply lines 492 and 494 and the water supply line493) that that engage with corresponding receiving holes in theconnection point 512. The E-prong connector 491 and receiving holes inthe connection point 512 are arranged so that a center lumen (the watersupply line 493) is arranged above, or otherwise out of, a common planeof the two outer lumens (the bicarbonate and acid supply lines 492 and494). In this way, it is ensured that the bicarbonate and acid supplylines 492 and 494 are properly connected since the E-prong connector 491cannot be engaged with the connection point 512 unless appropriatelyoriented. The E-prong connector 491 includes a pair of spring tabs 491 athat can be engaged with corresponding slots 512 a in the connectionpoint 512, e.g., when the prongs are properly seated in receiving holesof the connection point 512. With the tabs 491 a engaged in the slots512 a, the E-prong connector 491 cannot be easily removed from theconnection point 512, helping reduce the likelihood of an accidentaldisconnection. The E-prong connector 491 may be disconnected by pressingthe tabs 491 a toward each other so that barbs at the distal ends of thetabs 491 a disengage from the slots 512 a. The connection point 512 hassimilar spring tabs 512 b which allow the connection point 512 to beconnected to and disconnected from the front panel 511.

In accordance with another aspect of the invention, a disinfectconnector (not shown) engages with connection point 512 for use during adisinfection procedure. The disinfect connector has three parallelprongs having a similar orientation as the E-prong connector 491, sothat the prongs may engage with the receiving holes in connection point512. The channels in the prongs of the disinfect connector terminatewithin a common chamber within the disinfect connector. Thus, during adisinfect procedure, the bicarbonate flow line, acid flow line and waterflow line are all interconnected, permitting disinfection of each ofthese flow lines during the disinfect procedure. (This is shown as adashed inverted “T” line at 49 in FIG. 6).

In accordance with another aspect of the invention, the blood lines 203,204 are equipped with a connector that enables two types of connectionsto be made. One type of connection is a plug-in or press-in connectionby which the connector can be pushed into a receiving lumen and aleakfree connection made without requiring rotation of the connector orthe receiving lumen. A second type of connection is a screw-typeconnection by which a leakfree connection can be made by a threadedengagement of the connector with a complementary element. For example,FIGS. 27 and 28 show a perspective view and a side view of a blood lineconnector 202 that is used with the blood lines 203, 204 and that canengage with the blood line connection point 514 on the front panel 511.The connector 202 includes a tube connection end 202 a that connects tothe corresponding blood line 203, 204, and a patient access connectionend 202 b that is arranged to connect to both a patient access as wellas the connection point 514 to establish a leakfree connection. At thepatient access connection end 202 b, the connector 202 includes afrustoconical member 202 c that has an internally threaded portionarranged to engage with an externally threaded patient access. Forexample, the frustoconical member 202 c may be part of a male-type luerconnector that includes the central tube 202 e extending from the centerof the frustoconical member 202 c. When making the luer connection, thetube 202 e may extend into a female luer connector at the patient accessand the threaded portion on the interior of the frustoconical member 202c may engage with a thread on the female luer connector of the patientaccess (whether arterial or venous). Such luer connections are standardwhen connecting blood lines to a patient access. However, the connector202 may also be engaged with the connection point 514 by simply pushingthe patient access connection end 202 b into a receiving hole of theconnection point 514. When making this connection, the exterior of thefrustoconical member 202 c may engage with a suitable seat, or othersurface or element in the connection point 514 (such as a valve seat,O-ring, or other) so that a seal is formed between the frustoconicalmember 202 c and the connection point 514. The central tube 202 e mayalso, or instead, be used to engage with the connection point 514 toestablish a suitable seal. Locking arms 202 d that extend rearwardlyfrom the frustoconical member 202 c may engage with holes 514 a in theconnection point 514 (e.g., barbed portions on the arms 202 d may engagewith the holes 514 a) to help maintain the connector 202 in thereceiving hole of the connection point 514. The connector 202 may bereleased by pressing the arms 202 d toward each other (e.g., by pressingon finger depression portions at the distal ends of the arms 202 d),thereby disengaging the barbs from the holes 514 a, and withdrawing theconnector 202. Note that the connection point 514 may include springtabs 514 b to allow the connection point 514 to be selectivelyengaged/disengaged at the front panel 511. The connectors 202 may bemade in any suitable way, such as by molding of plastic as a singleunitary part.

The following are each incorporated herein by reference in theirentireties: U.S. Provisional Patent Application Ser. No. 60/903,582,filed Feb. 27, 2007, entitled “Hemodialysis System and Methods”; U.S.Provisional Patent Application Ser. No. 60/904,024, filed Feb. 27, 2007,entitled “Hemodialysis System and Methods”; U.S. patent application Ser.No. 11/787,213, filed Apr. 13, 2007 and published as U.S. PatentApplication Publication No. 2008/0058697 on Mar. 6, 2008, entitled “HeatExchange Systems, Devices and Methods”; U.S. patent application Ser. No.11/787,212, filed Apr. 13, 2007 and published as U.S. Patent ApplicationPublication No. 2008/0175719 on Jul. 24, 2008, entitled “Fluid PumpingSystems, Devices and Methods”; U.S. patent application Ser. No.11/787,112, filed Apr. 13, 2007 and published as U.S. Patent ApplicationPublication No. 2007/0253463 on Nov. 1, 2007, entitled “Thermal andConductivity Sensing Systems, Devices and Methods”; U.S. patentapplication Ser. No. 11/871,680, filed Oct. 12, 2007 and published asU.S. Patent Application Publication No. 2008/0208103 on Aug. 28, 2008,entitled “Pumping Cassette”; U.S. patent application Ser. No.11/871,712, filed Oct. 12, 2007, entitled “Pumping Cassette”; U.S.patent application Ser. No. 11/871,787, filed Oct. 12, 2007 andpublished as U.S. Patent Application Publication No. 2008/0253911 onOct. 16, 2008, entitled “Pumping Cassette”; U.S. patent application Ser.No. 11/871,793, filed Oct. 12, 2007 and published as U.S. PatentApplication Publication No. 2008/0253912 on Oct. 16, 2008, entitled“Pumping Cassette”; and U.S. patent application Ser. No. 11/871,803,filed Oct. 12, 2007 and published as U.S. Patent Application PublicationNo. 2008/0202591 on Aug. 28, 2008, entitled “Cassette System IntegratedApparatus.” In addition, the following are incorporated by reference intheir entireties: U.S. Pat. No. 4,808,161, issued Feb. 28, 1989,entitled “Pressure-Measurement Flow Control System”; U.S. Pat. No.4,826,482, issued May 2, 1989, entitled “Enhanced Pressure MeasurementFlow Control System”; U.S. Pat. No. 4,976,162, issued Dec. 11, 1990,entitled “Enhanced Pressure Measurement Flow Control System”; U.S. Pat.No. 5,088,515, issued Feb. 18, 1992, entitled “Valve System withRemovable Fluid Interface”; and U.S. Pat. No. 5,350,357, issued Sep. 27,1994, entitled “Peritoneal Dialysis Systems Employing a LiquidDistribution and Pumping Cassette that Emulates Gravity Flow.” Alsoincorporated herein by reference are a U.S. patent application Ser. No.12/038,474, filed Feb. 27, 2008 and published as U.S. Patent ApplicationPublication No. 2008/0253427 on Oct. 16, 2008, entitled “SensorApparatus Systems, Devices and Methods,” and a U.S. patent applicationSer. No. 12/038,648, filed Feb. 27, 2008 and published as U.S. PatentApplication Publication No. 2008/0216898 on Sep. 11, 2008, entitled“Cassette System Integrated Apparatus.”

While several embodiments of the present invention have been describedand illustrated herein, those of ordinary skill in the art will readilyenvision a variety of other means and/or structures for performing thefunctions and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the present invention.More generally, those skilled in the art will readily appreciate thatall parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the teachings of thepresent invention is/are used. Those skilled in the art will recognize,or be able to ascertain using no more than routine experimentation, manyequivalents to the specific embodiments of the invention describedherein. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto, the invention maybe practiced otherwise than as specifically described and claimed.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

What is claimed is: 1.-9. (canceled)
 10. A dialysis system comprising:an air trap; and a fluid pump configured to pump fluid from an upperinlet to a lower outlet of the air trap; the air trap comprising: acontainer having an approximately spherical or spheroid-shaped internalwall defining a chamber, the inlet of the air trap positioned at a topend of the container and the outlet of the air trap positioned at abottom end of the container, the inlet being offset from a vertical axisof the container such that fluid entering the chamber through the inletis directed to flow along the internal wall toward the outlet; whereinthe air trap is configured to accumulate undissolved gas from the fluidat the top end of the container, and the pump is configured to pump thefluid in a reverse direction from the outlet to the inlet of the airtrap to remove accumulated gas from the container.
 11. The system ofclaim 10, wherein the container is formed by an approximately sphericalshell.
 12. The system of claim 10, further comprising a dialyzer fluidlyconnected to the inlet of the air trap.
 13. The system of claim 10,further comprising a self-sealing port located at a top of thecontainer.
 14. The system of claim 13, wherein the self-sealing port isformed by a split septum.
 15. The system of claim 14, wherein the splitseptum is arranged to permit introduction of fluid into, and withdrawalof liquid from, the container by inserting a needleless device throughthe split septum.
 16. The system of claim 14, wherein the self-sealingport is arranged to be self-cleaning when disinfection liquid iscirculated through the container.
 17. The system of claim 16, wherein aninner surface of the self-sealing port is approximately flush with theinternal wall of the container at a top of the container.
 18. The systemof claim 16, wherein the self-sealing port is cleaned by introducingliquid into the container via the outlet and removing liquid from thecontainer via the inlet.
 19. The system of claim 10, wherein the inletis arranged to introduce blood into the container in a direction that isapproximately tangential to the approximately spherical orspheroid-shaped inner wall of the container.
 20. The system of claim 10,wherein the inlet is arranged to introduce blood into the container in adirection that is approximately perpendicular to the vertical axis ofthe container.
 21. The system of claim 10, further comprising a dialyzerand wherein the fluid pump is a blood pump having an outlet fluidlyconnected to a dialyzer, wherein the dialyzer is fluidly coupled to theinlet of the air trap such that fluid pumped from the blood pump outletby the blood pump passes through the dialyzer and to the air trap. 22.The system of claim 21, further comprising an arterial line fluidlycoupled to an inlet of the blood pump, and a venous line fluidly coupledto the outlet of the air trap.
 23. The system of claim 22, wherein theinlet of the blood pump is located above the outlet of the blood pumpand the air trap is located below the outlet of the blood pump.